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We're lucky Earth isn't caught in a permanent Ice Age

exoplanets life

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#1 grog

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Posted 19 September 2017 - 10:59 AM

We're lucky Earth isn't caught in a permanent Ice Age
 
 
 
 
16 September 2017
 
 
 
 
If we were just a fraction further from the Sun, life on Earth would be very different... or probably non-existent
 
The Earth might be more special than we previously thought. A new scientific study has found that if we were just a fraction further from the Sun, our planet would be locked in a never ending Ice Age.
 
The findings, published in the journal Earth and Planetary Science Letters, will help us understand what criteria to look for in Earth-like exoplanets.
 
For years, scientists have discovered a huge amount of evidence that shows the Earth is the perfect place for life.
 
"It has a magnetic field that protects us from the solar wind," says Martin Turbet, from Sorbonne Universitésin Paris. "It has an ozone layer that shields us from UV light, it has the right amount of water on the surface for both lands and oceans to exist."
 
Turbet and his colleagues have found another factor to Earth's list of exceptional qualities. The study looked at the effect of carbon dioxide condensation on cold planets during an Ice Age.
 
On planets slightly colder than Earth, they found CO2 would condense at the poles preventing it from escaping as a gas and warming up the planet through the greenhouse effect.
 
"We show in fact that the Earth is just at the right distance from the Sun to be able to escape from episodes of complete glaciation, that - we know - must have occurred 2.4Gy and 700My ago," he explains. Move the Earth away from the Sun by only 15 per cent, the team found, and it would be permanently frozen.
 
"We had some clues that CO2 condensation could occur on cold planets, and that it could affect the ability of Earth-like planets to escape from episodes of complete glaciation," Turbet says, "but no-one has ever been able to quantify it."
 
The results give us further clues as to where the habitable zone, the region in which it may be able to host liquid water, of an Earth-like planet lies, including discoveries in our backyard.
 
The past two years have been extremely successful when it comes to discoveries of potentially habitable exoplanets. The biggest discoveries include Proxima Centauri b, the closest exoplanet to Earth, and the seven planets of the TRAPPIST-1 system.
 
"It is widely believed that these Earth-size planets could be in synchronous rotation around their star, with one side permanently locked in the dark," Turbet says. "The nightside surface temperature of such planet can be so low that the CO2 would condense on it. And such process is of high relevance to assess the habitability of these newly discovered worlds."
 
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#2 grog

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Posted 19 September 2017 - 11:06 AM

What Was Frigid 'Snowball Earth' Really Like?
 
 
 
 
 
23 August 2013.
 
 
 
 
 
Three times in Earth's history, ice has covered the majority of the planet.
 
 
During vast ice ages millions of years ago, sheets of glaciers stretched from the poles almost to the equator, covering the Earth in a frozen skin. Conditions on the "snowball Earth," as scientists refer to it, made the planet a completely different place.
 
"We're essentially talking about another world," said Linda Sohl of the NASA Goddard Institute for Space Studies in New York.
 
In May, Sohl spoke with a small group at a lunchtime seminar, later posted online, about the evolution of the understanding of the snowball Earth and how it has changed as technology has improved. [50 Amazing Facts About Earth]
 
Continent-sized glaciers
 
By the early 1990s, scientists had found several unusual features that indicated something chilling had happened in the past. Glacial deposits of similar ages appeared on almost every continent. Evidence revealed that capped carbonates - limestone overlays formed by the ocean - lying on top of the glacial deposits had formed where they were found, rather than having migrated south from higher latitudes.
 
"There had been this growing consensus that we'd had some terrible ice ages back in the past," Sohl said.
 
These features appeared at three different times in Earth's history, at 750 million, 635 million, and 580 million years ago.
 
"Snowball events are extreme glaciations," Carl Stevenson, a geologist with the University of Birmingham in Great Britain, told Astrobiology Magazineby email. Stevenson is part of a separate project studying snowball events.
 
During normal ice ages, "ice sheets sort of pulse outward from the poles and retract," Stevenson said.
 
"In a snowball event, the pulse of glaciers seems to reach a tipping point for some reason, and the whole system goes into a snowball." Instead of retracting, the glaciers creep farther south.
 
Temperatures on a snowball Earth are estimated to have reached minus 58 degrees Fahrenheit (minus 50 degrees Celsius). As the ice spread, more heat was reflected back into space rather than absorbed by the planet, dropping temperatures down in a runaway effect that sped the formation of ice.
 
"If you can think of continent-size ice sheetssitting where Saudi Arabia is right now, that will give you an idea of how cold the environment seemed to be," Sohl said. [Gallery: Awe-Inspiring Glaciers]
 
The world remained almost completely frozen over during each of the three periods for around 10 million years before warming again. Scientists still aren't certain what caused temperatures to rise again, but volcanic activity is a strong suspect. Many rocks absorb carbon dioxide, but in a snowball scenario such formations would be covered, allowing the atmosphere-heating molecule to build up to a point where global warming could melt the ice.
 
Slushy or solid?
 
First proposed in 1992 by Joseph Kirschivink at the California Institute of Technology, the idea of an icy Earth lay dormant for six years until Harvard colleague Paul Hoffman published an article envisioning a world with a totally frozen ocean.
 
But an Earth where the water was 100 percent solid was a hard sell to some. At a workshop in Switzerland in the summer of 2006, 65 scientists - geologists, biologists, planet modelers and those in other fields - came together to discuss the possibilities and problems with such a world. 
 
"We spent a week thrashing through a bunch of things," Sohl said.
 
Ultimately, the evidence seemed against a completely ice-covered world. Biologists pointed out that a frozen ocean would block light, which should have resulted in mass extinctions that don't show up in the fossil record. Geologists raised the issue that the proposed shutdown of the water cycle was not compatible with evidence. Sohl felt that most people left the conference thinking that the oceans never froze completely.
 
Maroon glacial deposits lay on top of a grey carbonate reef. Though the photo was taken in Canada's Yukon Territory, the land mass lay in the tropics millions of years ago, indicating just how cold the planet got.  
 
"The alternative is that you have a slush ball," Sohl said. "Yes, there was a really bad ice age, but we had lots of open ocean."
 
"A slush ball is sort of a halfway scenario where, instead of a total 'white out,' there are gaps in the ice with open water," Stevenson said.
 
Sohl describes a world where the heat is concentrated around the equator, leaving a band of liquid water where life could survive. [Wipe Out: History's Most Mysterious Extinctions]
 
Better technology, better models
 
Computer simulations are limited by the technology that ran them, and programs have come a long way in 15 years.
 
"Earlier models were more restricted by the computers they ran on, and so when they approximated the real world, those approximations were quite crude," Gavin Schmidt told Astrobiology Magazineby email. Schmidt leads the program that developed and maintains the GISS-E2 simulations, a climate model program that Sohl used to simulate the conditions of a near-frozen Earth. GISS-E2 has a variety of configurations with technical differentiations.
 
Today's programs can break things into smaller pieces and work with more details than the programs that modeled the first ideas of icy Earths.
 
"The earliest models dealt mainly with the lower atmosphere; now they include the ocean, sea ice, land surfaces, the carbon cycle, aerosols, atmospheric composition, the stratosphere and above, and so on," Schmidt said.
 
The first versions of GISS-E2 were developed in the early 1980s, but the program has been updated and tweaked a number of times with the help of a variety of people.
 
"It is very much a group effort, including oceanographers, meteorologists, mathematicians, computer scientists, and others," Schmidt said.
 
Climate models such as GISS-E2 can give scientists not only a view of Earth's possible past, but can also provide peeks into the future. Upcoming changes will also help the simulation to have greater flexibility, allowing it to be used for other planets.
 
A second look
 
As part of the May seminar, Sohl presented information about her current ongoing research into the two older icy periods. Using the more modern programs, she has engaged in rerunning simulations her team originally performed in the mid-1990s. With more experiments to perform, the recent research has not yet been subject to peer review or publication.
 
In both sets of experiments, the land was barren. The presence or absence of plants affects the reflectivity, or albedo, of a planet, which in turn feeds into how fast it heats up.
 
"Plants on land didn't show up until about 460 million years ago," Sohl said. "At best, there might have been some lichens or something like that on land, but that's really controversial."
 
Graphic showing the progression towards a Snowball Earth.
 
The original experiment assumed standard desert conditions, but for the modern version, the scientists used a spot in the barren Gobi desert as an example of the proportions that could occur on a desolate early Earth.
 
Both projects simulated 60 years, at which point there were no more changes. Today, a simulation of that time frame lasts 12 hours; the original run-through lasted far longer.
 
Sohl discussed seven experiments with the group. The first was a basic control run, using preindustrial conditions. She also ran three simulations each for the two glacial intervals, changing the brightness, or luminosity, of the sun. Early in the history of the solar system, the sun was dimmer, which would also have affected the development of the snowball Earth.
 
In the original program, land masses were collapsed into a Pangaea supercontinent state, but for today's experiments the team decided that relocating the continents didn't have a significant effect on changing the planet's albedo. But leaving the world as is created a number of nooks and crannies for ice to pile up in, slowing the program down. Sohl said that future runs would contain a simplified topography.
 
Scientists don't know exactly what triggers the tipping point for a snowball Earth. One surprising result of Sohl's recent simulations was that extreme conditions weren't a requirement. A snowball Earth was created using conditions from before the relatively recent Industrial Age.
 
Another shock was the similarity of the results for the younger ice age even when the initial conditions were changed. Simulations with the solar luminosity set to the maximum suspected levels while the carbon dioxide levels were minimized produced comparable conditions to the sun shining at today's brightness.
 
"I was not prepared for these runs to be so similar to each other at this point," Sohl said.
 
Going forward, Sohl hopes to investigate other modifications that E2-R will allow, including changing the length of the days to the 21.9 hours it once took the Earth to turn on its axis.  As technology allows climate models to account for a wider range of variables, scientists should be able to better understand the driving forces that created and maintained a slushy snowball planet.
 
But if the Earth has become a giant ice block three times, could it happen again?
 
"I don't think they would happen again during human existence," Stevenson said.
 
 

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#3 grog

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Posted 19 September 2017 - 11:08 AM

What If Earth's Magnetic Poles Flip?
 
 
 
 
10 February 2012.
 
 
 
 
 
If Earth's magnetic field reversed, compasses would point toward Antarctica.
 
 
The end of the world as we know it could come in any number of ways, depending on who you ask. Some people believe global cataclysm will occur when Earth's magnetic poles reverse. When north goes south, they say, the continents will lurch in one direction or the other, triggering massive earthquakes, rapid climate change and species extinctions.
 
The geologic record shows that hundreds of pole reversals have occurred throughout Earth's history; they happen when patches of iron atoms in Earth's liquid outer core become reverse-aligned, like tiny magnets oriented in the opposite direction from those around them. When the reversed patches grow to the point that they dominate the rest of the core, Earth's overall magnetic field flips. The last reversal happened 780,000 years ago during the Stone Age, and indeed there's evidence to suggest the planet may be in the early stages of a pole reversal right now.
 
But should we really fear this event? What will actually happen when north-pointing compasses make a 180-degree turn toward Antarctica? Will the continents tear themselves apart, or are we in store for much more mundane changes?
 
Weak field
 
"The most dramatic changes that occur when the poles reverse is a very large decrease of the total field intensity," said Jean-Pierre Valet, who conducts research on geomagnetic reversals at the Institute of Earth Physics of Paris. [5 Ways the World Will Change Dramatically this Century]
 
Earth's magnetic field takes between 1,000 and 10,000 years to reverse, and in the process, it greatly diminishes before it re-aligns. "It's not a sudden flip, but a slow process, during which the field strength becomes weak, very probably the field becomes more complex and might show more than two poles for a while, and then builds up in strength and [aligns] in the opposite direction," said Monika Korte, the scientific director of the Niemegk Geomagnetic Observatory at GFZ Potsdam in Germany.
 
 
 
Supercomputer models of Earth's magnetic field. On the left is a normal dipolar magnetic field. On the right is the sort of complicated magnetic field Earth has leading up to a reversal.
Supercomputer models of Earth's magnetic field. On the left is a normal dipolar magnetic field. On the right is the sort of complicated magnetic field Earth has leading up to a reversal.
Credit: NASA
 
 
 
The scientists say it's the weak in-between phase that would be roughest on Earthlings.
 
According to John Tarduno, professor of geophysics at the University of Rochester, a strong magnetic field helps protect Earth from blasts of radiation from the sun. "Coronal mass ejections (CMEs) occasionally occur on the Sun, and sometimes hurtle directly toward Earth," Tarduno said. "Some of the particles associated with CMEs can be blocked by Earth's magnetic field. With a weak field, this shielding is less efficient."
 
The charged particles bombarding Earth's atmosphere during solar storms would punch holes in Earth's atmosphere, and this could hurt humans. "Ozone holes, like that over Antarctica (which today are due to an entirely different cause related to man) could form as solar particles interact with the atmosphere in a cascade of chemical reactions. These 'holes' would not be permanent, but might be present on one- to 10-year timescales - arguably important enough to be a concern in terms of skin cancer rates," Tarduno said. [Will Sunscreen Protect You from the Upcoming Solar Flares?]
 
Valet agrees that a weak magnetic field could lead to the formation of ozone holes. He wrote a paper last year proposing a direct link between the demise of Neanderthals, our evolutionary cousins, and a significant decrease of the geomagnetic field intensity that occurred exactly at the same period. (That time, the lead-up to a geomagnetic reversal appears to have been "aborted"; the field weakened but didn't end up flipping.)
 
Other scientists aren't convinced that there's a connection between pole reversals and species extinctions. "Even if the field becomes very weak, at the Earth's surface we are shielded from radiation by the atmosphere. Similarly as we cannot see or feel the presence of the geomagnetic field now, we most likely would not notice any significant change from a reversal," Korte said.
 
Our technology definitely would be in danger, however. Even now, solar storms can damage satellites, cause power outages and interrupt radio communications. "These kinds of negative influences clearly will increase if the magnetic field and thus its shielding function became significantly weaker, e.g. during a reversal, and it will be important to find mitigation strategies," she told Life's Little Mysteries.
 
One additional worry is that a weakening and eventual reversal in the field would disorient all those species that rely on geomagnetism for navigation, including bees, salmon, turtles, whales, bacteria and pigeons. There is no scientific consensus on how those creatures would cope.
 
Continental shifts?
 
Many of the disaster scenarios associated with geomagnetic pole reversals in popular imagination are pure fantasy, the scientists said. There definitely won't be any break-up or shift of the continents.
 
The first proof is the geologic record. When the last pole switch happened, "no worldwide shifting of continents or other planet-wide disasters occurred, as geoscientists can testify to from fossil and other records," said Alan Thompson, head of geomagnetism at the British Geological Survey.
 
The scientists explained that changes in the Earth's liquid core happen on a completely different distance and timescale than convection in the Earth's mantle (which causes Earth's tectonic plates to shift, moving the continents). The liquid core does indeed touch the bottom of the mantle, but it would take tens of millions of years for changes in the core to propagate up through the mantle and influence the motion of the tectonic plates. In short, "there is no evidence from the geological past and in my opinion also no conceivable method that magnetic reversals couldtrigger Earthquakes," Korte said.
 
Sooner or later
 
The geomagnetic field is currently weakening, possibly because of a growing patch of reverse-alignment in the liquid core deep beneath Brazil and the South Atlantic. According to Tarduno, the strength of Earth's magnetic field "has been decreasing for at least 160 years at an alarming rate, leading some to speculate that we are heading toward a reversal."
 
 
 
Image of the South Atlantic Anomaly (SAA), the region where Earth's magnetic field is weakest, taken by the ROSAT satellite in the 1990s.
Image of the South Atlantic Anomaly (SAA), the region where Earth's magnetic field is weakest, taken by the ROSAT satellite in the 1990s.
Credit: NASA
 
 
 
The reversal might happen, or it might be aborted - Earth is too complex a system for scientists to know which outcome to expect. Either way, the process will drag on over the next few thousand years, giving us time to adjust to the changes. 
 
 

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#4 grog

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Posted 19 September 2017 - 11:11 AM

 
 
 
 
 
 
VIEWING EARTH AS AN EXTRA-SOLAR PLANET
 
 
 
What if another civilization had telescopes and spacecraft better than ours? Would Earth be detectable from another planet a few light-years away? Likewise, what will it take for us to detect life on an Earth-like planet within a similar distance? It's interesting to consider those questions, and now, there is data to help answer them. In December 1990, when the Galileo spacecraft flew by Earth in its circuitous journey to Jupiter, scientists pointed some of the instruments at Earth just to see how the old home planet looked from space. Since we knew life could definitely be found on Earth, this exercise helped create some criteria that if found elsewhere, would point to the existence of life there as well. But what if Earth's climate was different from what it is now? Would that signature still be detectable? And could potential biomarkers from extra solar planets holding climates much colder or warmer than ours be obvious? A group of researchers in France input some various criteria garnered from different epochs in Earth's history to test out this hypothesis. What did they find?
 
One of the most telling of the criteria from the Galileo flyby revealing life on Earth was what is called the vegetation red edge -a sharp increase in the reflectance of light at a wavelength of around 700 nanometers. This is the result of chlorophyll absorbing visible light but reflecting near infrared strongly. The Galileo probe found strong for this evidence on Earth in 1990.
 
Luc Arnold and his team at the Saint-Michel-l'Observatoire in France wanted to determine some different parameters where plant life similar to Earth's would still be detectable via the vegetative red edge on an Earth-like planet orbiting a star several light years away.
 
At that distance the planet would be a non-resolvable (in visible light) point-like dot, so the first question to consider is whether the red edge would be visible at different angles. The planet is likely to be rotating, and for example, on Earth, the continents that have the most vegetation are mainly in the northern hemisphere. If that hemisphere wasn't leading the view, would a bio-signature still be detectable? They also wanted to allow for the different seasons, where a hemisphere in winter would be less likely to have vegetative biomarkers than one in summer, and potential heavy cloud cover.
 
They also input different climate criteria from the last Quaternary climate extremes, using climate simulations have been made by general circulation models. They used data from the present time and compared that to an ice age, The Last Glacial Maximum (LGM) which occurred about 21,000 years ago. Temperatures globally were on the order of 4 degrees C colder than today, and ice sheets covered most of the northern hemisphere. Then, they used a warmer time, during the Holocene epoch 6,000 years ago, when the Earth's northern hemisphere was about 0.5 degrees C warmer than today. The sea level was rising and the Sahara Desert contained more vegetation.
 
Surprisingly, the researchers found even during winter in an ice age, the vegetation red signal would not be significantly reduced, compared to today's climate and even the warmer climate.
 
So if another Earth is out there, the vegetaion red edge should allow us to find that Earth-like planet. But we need better telescopes and spacecraft to find it.
 
The best hope on the horizon is the Terrestrial Planet Finder. ESA has a similar instrument in the works called Darwin.
 
The teams behind these instruments say they could spot Earth-like planets orbiting stars at distances of up to 30 light years with an exposure measured in a couple of hours.
 
Arnold's team says that spotting the signs of life on such a planet would be much harder. The vegetation red edge might only be seen with an exposure of 18 weeks with a telescope like the Terrestrial Planet Finder's. An 18 week exposure of a planet orbiting another star would be an almost impossible task.
 
So when might we eventually see vegetation on another planet? The Terrestrial Planet Finder (TPF) looks unlikely to be launched before 2025 and even then might not have the power to do the job.
 
More ambitious telescopes later in the century, such as a formation of 150 3-meter mirrors would collect enough photons in 30 minutes to freeze the rotation of the planet and produce an image with at least 300 pixels of resolution, and up to thousands depending on array geometry. "At this level of spatial resolution, it will be possible to identify clouds, oceans and continents, either barren or perhaps (hopefully) conquered by vegetation," the researchers write.

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#5 grog

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Posted 19 September 2017 - 11:14 AM

The Universe Has Probably Hosted Many Alien Civilizations
 
 
 
 
 
 
 
 
Many other planets throughout the universe probably hosted intelligent life long before Earth did, a new study suggests.
 
The probability of a civilization developing on a potentially habitable alien planet would have to be less than one in 10 billion trillion - or one part in 10 to the 22nd power - for humanity to be the first technologically advanced species the cosmos has ever known, according to the study.
 
"To me, this implies that other intelligent, technology-producing species very likely have evolved before us," said lead author Adam Frank, a professor of physics and astronomy at the University of Rochester in New York. [13 Ways to Hunt Intelligent Alien Life]
 
Do you believe alien life exists elsewhere in the universe?
 
 Yes - We may not have found them yet, but they're out there. 
 
 No - Aliens are just part of science fiction.
 
 I'm not sure 
 
Get Results
 
"Think of it this way: Before our result, you'd be considered a pessimist if you imagined the probability of evolving a civilization on a habitable planet was, say, one in a trillion," Frank said in a statement. "But even that guess - one chance in a trillion - implies that what has happened here on Earth with humanity has in fact happened about 10 billion other times over cosmic history."
 
In 1961, astronomer Frank Drake devised a formula to estimate the number of extraterrestrial civilizations that may exist today in the Milky Way.
 
Adam Frank and co-author Woodruff Sullivan of the University of Washington were interested in the odds that intelligent aliens have ever existed anywhere in the universe. So they tweaked the famous Drake equation, coming up with an "archaeological version" that doesn't take into account how long alien civilizations may last.
 
Frank and Sullivan also incorporated observations from NASA's Kepler space telescope and other instruments, which suggest that about 20 percent of all stars host planets in the life-friendly, "habitable zone," where liquid water could exist on a world's surface.
 
The researchers then calculated the probability that Earth was the universe's first-ever abode for intelligent life, after taking into account the number of stars in the observable universe (about 20 billion trillion, according to a recent estimate).
 
"From a fundamental perspective, the question is, 'Has it ever happened anywhere before?'" Frank said. "Our result is the first time anyone has been able to set any empirical answer for that question, and it is astonishingly likely that we are not the only time and place that an advanced civilization has evolved."
 
But this doesn't mean that there are lots of intelligent aliens out there, just waiting to be contacted, the researchers stressed.
 
"The universe is more than 13 billion years old," Sullivan said in the same statement. "That means that even if there have been 1,000 civilizations in our own galaxy, if they live only as long as we have been around - roughly 10,000 years - then all of them are likely already extinct. And others won't evolve until we are long gone. For us to have much chance of success in finding another 'contemporary' active technological civilization, on average they must last much longer than our present lifetime."
 
(The 10,000-year figure cited by Sullivan refers to humanity's development of agriculture and other "rudimentary" technologies; mankind has been capable of sending radio waves and other electromagnetic signals out into the cosmos for just a century or so.)

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#6 grog

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Posted 19 September 2017 - 11:21 AM

The Closest Known Potentially Habitable Planet Is 13 Light-Years Away
 
 
 
 
 
 
 
Astronomers have discovered two new super-Earths orbiting an ancient 11.5 billion year-old star a "mere" 13 light-years from here. One planet is in the habitable zone, prompting a researcher to wonder what kind of life could have evolved over such a long period.
 
For comparison, these exoplanets are 2.5 times older than Earth and only two billion years younger than the universe itself, which is about 13.7 billion years-old. If there's life on one of these planets - and that's a big if - it's been there for a potentially very long time.
 
And amazingly, it's "only" 13 light-years away. That makes it the closest confirmed potentially habitable exoplanet to Earth, not including Tau Ceti e, an unconfirmed planet located 11.9 light-years away. The next best bet after that is Gliese 581-d, which is 20.2 light-years away. It's also worth noting that Alpha Centauri, the closest star to our own - just 4.3 light-years away - hosts a planet, but it's parked way to close to the sun to be habitable (its year is a mere three days long).
 
Five new planets discovered just 12 light-years away
 
Astronomers have discovered a habitable planet 20 light years away
 
Orbiting a nearby red dwarf star called Gliese 581 are 6 planets. One of them is a rocky ball,…
 
Scientists discover a planet in Alpha Centauri, the star system nearest Earth
 
This is huge. We've discovered a lot of exoplanets, including rocky Earth-like ones, in…
 
So, a bit about this discovery. These planets orbit Kapteyn's Star, a halo red dwarf that was discovered at the end of the 19th century by Dutch astronomer Jacobus Kapteyn. It's the second fastest moving star in the sky and the 25th closest star to our solar system. With a magnitude of nine it can be seen through a telescope or with a pair of binoculars. It has a third of the mass of the sun and can be seen in the southern constellation of Pictor.
 
New data analyzed by astronomers at the Queen Mary School of Physics now shows that Kapteyn is not alone; it's orbited by at least two super-Earths, Kapteyn-b and Kapteyn-c. The astronomers were looking at data collected from the HARPS spectrometer at the ESO's La Silla observatory in Chile. The findings were corroborated by data from HIRES at Keck Observatory and PFS at Magellan/Las Campanas Observatory. The new planets were found using the Doppler Effect, which shifts the star's light spectrum depending on its velocity. This technique allows astronomers to determine several properties of extrasolar planets, including their masses and orbital periods.
 
A Temperate Super-Earth
 
Kapteyn-b has a mass that's nearly five times that of Earth's. It may be able to sustain liquid water at its surface; Kapteyn-b orbits every 48 days, which places it in the circumstellar habitable zone. That might sound close - and it is - but keep in mind that red dwarfs are not as powerful as G-type main sequence stars like our own. The astronomers, a team led by Guillem Anglada-Escude, say it's the oldest potentially habitable planet known to date. And by my calculations, it's the closest known and confirmed potentially habitable planet to Earth.
 
The other planet, Kapteyn-c, is less promising in terms of habitability. It's a massive super-Earth that's seven times heavier than Earth, requiring about 121 days to complete an orbit. Astronomers think it's too cold to support liquid water.
 
The atmospheric composition of the planets is not known.
 
Related: A planet so big they're calling it Godzilla | Red dwarfs may sterilize habitable planets
 
Astronomers Discover the "Mega Earth," an Entirely New Type of Planet
 
Meet the "Mega Earth." Described today by astronomers from the Harvard-Smithsonian Center …
 
Solar Winds From Red Dwarfs May Be Sterilizing Habitable Zone Planets
 
Red dwarfs stars, the most common stars in the galaxy, are bathing planets in their habitable zones …

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#7 grog

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Posted 19 September 2017 - 11:24 AM

Speculations on Communications With Other Planet Civilizations - [Project OZMA 1959-1960]
 
 
 
 
 
 
 
 
DURING our lifetime several events have occurred which have had tremendous significance to us all. The first nuclear explosion in 1945 and the Soviet’s Sputnik I are two striking examples. Reception and eventual change of intelligent information with some sort of civilization now in existence on another planet certainly would be an event of tremendous importance to us all. I believe that such an accomplishment appears to be most possible within the next decade. Since this subject should he of utmost interest to all radio amateurs I will attempt in this short article to bring you up to date on the basic premises for such startling speculations and, of more importance, what is being done to bring such an event to reality.
 
Life on other Planets
 
Before embarking on the radio communications involved it is necessary to establish that there is a reasonable probability of life existing on other planets capable of generating radio signals. Although such speculations have been going on for years, within the past three months three excellent articles have been published which put the problem clearly in focus. The first was published in the British journal Nature (September 19, 1959, page 844) by Giuseppe Cocconi and Philip Morrison of Cornell University. This paper was quickly followed by an article in the January, 1960, issue of Sky and Telescope, by Frank D. Drake, “How Can We Detect Radio Transmissions from Distant Planetary Systems”, and another in the January 2, 1960, issue of the Saturday Review by John Lear entitled “The Search for Intelligent Life on Other Planets”. This article is a digest of these three with a few “amateur” type speculations of my own.
 
Concerning life on other planets, the following highly simplified concept is advanced: Stars (such as our sun) are mixtures of hot gases and have been in existence for finite times. It would appear that the formation of planets and eventually “life” is some sort of function of time, temperature, and ingredients. If the proper elements are put in the “pot” and cooked long enough things happen and eventually something like a human could be produced. Billions of years are required to produce intelligent beings from a “potful” of organic molecules.
 
Astronomers have examined the spectral distribution, temperature, and age of many “seeable” stars and have come up with varying estimates of the probability of planets within the vicinity of these stars having some sort of life that could eventually generate radio transmissions. These estimates range from one star in four to as low as one star in a million with such qualifications. These odds have seemed high enough so that at least one qualified organization is getting ready to try to receive such transmissions.
 
An Active Program
 
As far as I can determine the only active program is under the direction of Frank D. Drake of the National Radio Astronomy Observatory at Green Bank, West Virginia. Drake has spent much of his 29 years in radio astronomy. He received his undergraduate training in physics from Cornell and his graduate training, resulting in a Ph.D. in radioastronomy, at Harvard. He states that he has never become a radio amateur because he is “too busy” but he is quite interested in the reaction of the amateur to his program. Drake has proposed a very interesting premise which would indicate that we electronically oriented types are very fortunate to have picked this particular century of centuries to have come into existence since 50 years ago there would have been no place for our talents and 50 years from now electronics as applied to communications will become as pedestrian as a 60 c.p.s. generator. I quote directly from his article.
 
“What search frequency would be best? Consider what might be called the principle of technical perfection. It is only about 50 years since radio communication was invented, yet we have already very nearly achieved technically perfect instruments, and within 50 more years we should have them. By technical perfection we mean that the limits of communication-system sensitivities are not set by deficiencies in the apparatus, such as receiver noise, but by natural phenomena over which man has no control. This is a state in which further improvements in apparatus will not improve the operational results.
 
"A century is only about a hundred-millionth of the age of our galaxy. Thus, on the galactic time scale, a civilization passes abruptly from a state of no radio ability to one of perfect radio ability. If we could examine a large number of lifebearing planets, we might expect to find in virtually every case either complete ignorance of radio techniques, or complete mastery. This is the principle of technical perfection. Our civilization may be one of an extremely small minority in transition between the two possible states - this, in fact, may be the only major feature in which man is unique.
 
“Therefore, it may be logical to assume that the civilizations we might detect possess complete mastery of radio already. The transmissions we seek will obviously be very powerful ones, in which large information transfer over long distances is being attempted. Frequencies will be chosen for which the natural limitations on performance are least. Two of these limitations are important: galactic radio noise emission, and noise from the planetary atmosphere, if reception from beneath the atmosphere is being attempted. “Both these emissions insert noise into the receiver, and have the same effect as though the receiver itself were noisy.
 
The graph (Fig. 1) shows for the earth the radio-sky temperature produced by each of these sources of noise, and their combined effect. This last would be the excess receiver noise temperature of an otherwise perfect receiver. Obviously, the best frequencies to use for our search are those where this total sky temperature is least. “For instance, from beneath the atmosphere of a planet like the earth, the band from 1000 to 10,000 megacycles per second would be the optimum for reception of long-range transmissions. If, however, reception is being done from above the atmosphere, as the principle of technical perfection and our own success with satellites suggest, frequencies above 10,000 megacycles are also good candidates.”
 
The almost unanimous recommendation for the choice of a “search” frequency is the region around 1420 Mc. (21 cm.). In 1951 Dr. Harold Ewen, then at Harvard, and now the very active president of the Ewen-Knight Corp. in Natick, Mass., discovered that in the vast, cool regions of space there is considerable radiated energy at approximately 1420 Mc. This radiation comes from the collision of neutral, highly kinetic hydrogen atoms which although they have a density of only 1 per cubic centimeter occasionally collide and one collision in eight is of the type that radiates at 1420 Mc. This radiation is strong enough so that depending on the aperture of the dish of the radio telescope, it can be detected at great ranges. Dr. Drake estimates that as many as 15 radio telescopes throughout the world are observing 1420-Mc. outer space radiation on a 24-hour basis. Astrophysicists such as Cocconi and Morrison of Cornell have postulated that since the interest in the 1420-Mc. radiation of cool, interstellar hydrogen is so strong here on earth, scientists on other planets must also be probing this region to learn more about their galaxy. Hence they have suggested that transmissions very near this frequency might be used to contact our earth. Drake, who is also an astrophysicist, and who probably had no real alternate candidate frequency for such a search, has embarked on a very ambitious program on 1420 Mc. which I will cover in the latter part of this article.
 
A Couple of Approaches
 
Before doing so I would like to advance two obvious, but non-astrophysical approaches to the problem. Drake has made the reasonable assumption that some of the most likely civilizations on other planets have long since passed through the critical 100 years of radio development. Is it not logical that a similar critical period exists during which a civilization undergoes the transition from being confined to the ground to baying thorough mastery of the space region within a reasonable distance from his own planet. It would seem to me that some such other planet has long since categorized our earth as a suitable candidate for “civilization brewing” and has been watching us and other suitable planets on a routine, automatic basis from sophisticated radiotelescopes on stable space platforms outside of their own atmosphere.
 
If such is the case, we can make two further assumptions. First, that like any good radio amateur listening for DX, they will transmit back near the frequency they first heard on a regular basis, and, second, that the millimeter wave region which has advantages which I will shortly describe is available to them both for transmission and reception.
 
I believe that most of the earlier transmissions from our earth were confined by the ionosphere due to their relatively low frequency. However, sometime around 1936—1938 enough power was radiated routinely on frequencies above 30 Mc. that some of it escaped to outer space where, depending on the sensitivity of the other civilization’s receiving installation, it may have been heard. The first British coastal radar chain and the Yankee network 49.3-Me. 500-kw. e.r.p. f.m. station W43B on top of Mount Asnebumskit are two good examples of stations that might have gotten “through.” Drake, who has almost completely ruled out the possibility of signals coming from other planets within our solar system, has stated that he will concentrate his initial listening to the regions near the two solar-type stars Tau Ceti and Epsilon Eridani which are 11 light years away. If we assume that the round trip then takes 22 years, it is interesting to note that 1938 + 22 = 1960. Since this might be the big year, on a long-shot basis it might he very worthwhile to listen to the region from 30 to 50 Mc. with suitable arrays pointed toward these stars when the m.u.f. is lower than 30. ‘With the present earth state of the art of receiving equipment plus the lugh background noise (see Fig. 1), we must rely on the transmitters on the other planet being most powerful to overcome our deficiencies. Drake believes that the sought-after-signals will of necessity be narrow band and with no spectacular form of modulation. Doppler shift will be evident due to the relative motion of the receiver and transmitter. This shift plus direction may be the distinguishing characteristics of this signal.
 
Unfortunately, because of previous experience the civilization on the other planet may decide that it is too difficult to try to contact us during our 100 years of transition to radio maturity since during this period they may have to compensate for our lack of an outside-of-atmosphere space platform, plus our inadequate receivers, transmitter, and perhaps unsophisticated correlation detecting schemes.
 
If he does elect to wait until we mature, the first communication will probably not take place at 30 Mc. or 1420 Mc., but more than likely between two outer atmosphere space platforms operating with very high power in the millimeter wave region above 30 kMc. Here we will have the obvious advantages of no atmospheric absorption plus the capability of generating, with relatively small antennae, very high effective radiated powers over very narrow beam widths. In addition, the vast number of megacycles available in this region would provide bandwidths for very fast rate of intelligence delivery per second. However, unless something really new shows up, we will still be inhibited by what now appears to be the remarkably slow speed of light in exchanging such intelligence.
 
Project Ozma
 
Enough of such speculation. Let us return to Drake. With luck in March, 1960, the National Radio Astronomy Observatory in Green Bank, West Virginia, will be listening near 1420 Mc. from an 85-foot telescope such as shown in Fig. 2. The following rule of thumb applies to reception of 1420 Mc. The distance in light years at which strong present-day transmitters can be detected is about equal to the diameter of the parabolic reflector in feet divided by 10. Thus, Drake’s telescope could pick up present-day “earth” style transmitters at a distance of 8.5 light years. The fact that he is concentrating on stars at 11 light years distance implies that he is hopeful that the engineers of the Tau Ceti and Epsilon Eridani planet systems have progressed far beyond our present techniques.
 
Fig. 2 - A typical radio telescope
 
"Frank Drake conducted Project Ozma, the world's first modern SETI experiment, from this 85 foot (26m) diameter dish at the National Radio Astronomy Observatory, Green Bank WV. On 8 April 1960, he detected a strong periodic pulsed signal while aimed at the nearby sun-like star Epsilon Eridani. The signal at first seemed to exhibit many of the characteristics we would expect of an extra-terrestrial message. When the signal repeated five days later, Dr. Drake tracked it across the sky with a small waveguide horn antenna, and determined it to be interference from a passing high-altitude aircraft. All subsequent SETI experiments have been similarly plagued by false hits.
 
 
Drake’s project is called Ozma after the beautiful princess of imaginary Oz. His system is quite complex and is described by him in his recent article as follows.
 
“A block diagram (Fig. 3) is given here of the Ozma radiometer, which operates near 1420 megacycles. It is essentially a highly stable narrow-band superheterodyne receiver, which utilizes the principles of both the Dicke radiometer and the d.c.-comparison type (see November 1959, Sky and Telescope).
 
Fig. 2
 
“Two horns are placed together at the focus of the parabolic antenna, in order to eliminate terrestrial interference to some extent. These horns give the antenna two beams, one to point at the star under study, the other off into space near the star. As the electronic switch connects first one horn and then the other to the receiver, the telescope will look alternately at the star and at the sky beside it. Any radiation from the star will then enter in pulses whose duration is controlled by the switch. The synchronous detectors near the output end of the circuit will respond only to pulses synchronized with the switch, thus detecting only the desired signal. Receiver noise is eliminated, and also terrestrial disturbances.
 
“Interference generally enters a radio telescope antenna through the horns directly, without a reflection from the paraboloid. In that case, both horns should receive the interfering signal with the same strength, and when the switch changes from one horn to the other there will be no change of level iii the interference entering the receiver. As a result, the interference signal is not pulsed, and the synchronous detectors ignore it.
 
“In the present receiver, immediately after the switch there comes a reactance [i.e., parametric] amplifier, to be replaced later with a maser. The amplifier, which gives the radiometer high sensitivity, was built by Ewen-Knight Corp., while the electronic switch was made by H. Hvaturn of NRAO. “The signal then undergoes four frequency conversions, this many being necessary because the final intermediate frequencies are very low, due to the narrow bandwidth requirements. The frequency received by the radiometer is directly dependent on the frequencies of the four oscillators, whose output signals beat with the true signal to produce the intermediate frequencies. In our specifications all four oscillators must hold their frequencies constant to better than one cycle per second on 100 seconds, if the over-all received frequency is also to be that constant.
 
“This is a most difficult requirement for the first oscillator, because its final frequency is about 1390 megacycles and it therefore must remain constant to one part in a billion. This accuracy is achieved by means of a special quartz crystal oscillator, the crystal being kept at a very constant temperature in an oven within an oven. The output of this oscillator is multiplied in frequency to give the desired final frequency. “A marker-frequency generator is used to provide weak signals from the output of the very stable oscillator at many fixed frequencies. These signals are inserted into the receiver for determining the exact frequency on which the receiver is operating, allowing the detection of Doppler effect.
 
“After the fourth intermediate-frequency amplification, two filters pick out a broad band of noise, called the comparison band, and a narrow one designated the signal band. The gain of these filters is adjusted so that when very broadband noise enters them their total outputs are equal. When these outputs are passed into the differencing circuit, its output is zero. However, a narrow-hand signal fills only some of the frequencies of the filter for the comparison band, but all of those in the signal-band filter. The output of the narrow-band filter is then greater than that of the broad-band one, and there is a net output from the differencing circuit. This use of the d.c. -comparison circuit makes the radiometer respond only to narrow-band signals. As drawn here, the radiometer is set up for signals for about 40-cycles-per-second bandwidth. In the actual receiver, the electronic filters have variable bandwidths that may be quickly adjusted to desired values.
 
“The filters placed before the synchronous detectors pass only the frequencies to which the detectors will respond, and reject other frequencies that might cause them to operate improperly. “We see that an output from the final synchronous detector will occur only when receiving a narrow band signal from a direction in which one of the antenna beams is pointing - the desired interstellar signal. The integrator only averages the signal strength over a chosen interval. The other two synchronous detectors and integrators connected directly to the comparison-band and signal-band channels monitor the performance of the radiometer.”
 
The amateur might well ask what position he could play in such an ambitious project. Such installations as just described don’t lend themselves to back yard installations or amateur pocketbooks. Two suggestions are put forward: If your interests are really strong in the field, perhaps the best approach is to get a job at a radio astronomy observatory. The January issue of Sky and Telescope, for instance, has an advertisement seeking a radio operator for its 85-foot telescope.
 
Secondly the building of a microwave radio telescope is a good type of club activity. The writer knows of several such projects which will shortly be in operation for amateur moon-bounce communications on 1296 Mc. (One of these is operated by Sam Harris, W1FZJ.) Incidentally, Drake would like to use amateur 1296-Mc. moon-bounce transmissions for calibration signals. Although the previous authors on this subject have demonstrated remarkable restraint on this score, I believe that it would not be appropriate to close this article without some speculation of what might transpire on that eventful day when Drake (a really appropriate name) or some future space-listener actually hears a signal bearing intelligence from another planet.
 
I am sure that he will have considerable difficulty in verifying its source first to himself, then to his sponsors and eventually his nation. Actually, unscrambling the intelligence will be a job that will need more than the classic Rosetta Stone that linked the Grecian and ancient Egyptian languages.
 
Drake stated that if the signal is very weak, requiring integration techniques to establish existence, he will agitate for use of a larger dish, such as the big Navy 600-footer which is now under construction. However, if the signals are strong enough, they will obviously be recorded and analyzed by the best cryptographic methods available.
 
The problem of attracting the attention at the other end over a span of, say, 22 years seems almost insurmountable. I could conjure up many more potential problems of a technical, data handling, and psychological nature. However, the rewards to the nation and total earth population could more than balance the difficulties encountered.
 
It is dangerous to assume that the inhabitants of other planets are similar to us. However, there must he some important common denominators. A look at such a civilization as ours even 50 years ahead not to mention thousands of years in the future, must provide solutions to medical, social, technical, and many other problems that would greatly benefit mankind . . . perhaps the cure of cancer and a cheaper version of the Beefeater Martini.
 
I wish to thank the editors of Sky and Telescope and Frank D. Drake for their help in this article and to express my appreciation of the many ideas on this subject provided by Dr. Harold Ewen of Ewen-Knight, Inc., and Messrs. F. S. Harris and H. Cross of Microwave Associates, Inc.

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#8 grog

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Posted 19 September 2017 - 11:28 AM

Snowball Earth Hypothesis
 
 
 
 
29 November 2016.
 
 
 
 
The Snowball Earth hypothesis proposes that Earth's surface became entirely or nearly entirely frozen at least once, sometime earlier than 650 Mya (million years ago). Proponents of the hypothesis argue that it best explains sedimentary deposits generally regarded as of glacial origin at tropical paleolatitudes, and other otherwise enigmatic features in the geological record. Opponents of the hypothesis contest the implications of the geological evidence for global glaciation, the geophysical feasibility of an ice- or slush-covered ocean,[3][4] and the difficulty of escaping an all-frozen condition. A number of unanswered questions exist, including whether Earth was a full snowball, or a "slushball" with a thin equatorial band of open (or seasonally open) water.
 
The snowball Earth episodes occurred before the sudden radiation of multicellular bioforms, known as the Cambrian explosion. The most recent snowball episode may have triggered the evolution of multicellularity. Another, much earlier and longer snowball episode, the Huronian glaciation, which occurred 2400 to 2100 Mya, may have been triggered by the first appearance of oxygen in the atmosphere, the "Great Oxygenation Event."
 
 
History[edit]
 
Sir Douglas Mawson (1882-1958), an Australian geologist and Antarctic explorer, spent much of his career studying the Neoproterozoic stratigraphy of South Australia, where he identified thick and extensive glacial sediments and late in his career speculated about the possibility of global glaciation.[5]
 
Mawson's ideas of global glaciation, however, were based on the mistaken assumption that the geographic position of Australia, and that of other continents where low-latitude glacial deposits are found, has remained constant through time. With the advancement of the continental drift hypothesis, and eventually plate tectonic theory, came an easier explanation for the glaciogenic sediments - they were deposited at a point in time when the continents were at higher latitudes.
 
In 1964, the idea of global-scale glaciation reemerged when W. Brian Harland published a paper in which he presented palaeomagnetic data showing that glacial tillites in Svalbard and Greenland were deposited at tropical latitudes.[6] From this palaeomagnetic data, and the sedimentological evidence that the glacial sediments interrupt successions of rocks commonly associated with tropical to temperate latitudes, he argued for an ice age that was so extreme that it resulted in the deposition of marine glacial rocks in the tropics.
 
In the 1960s, Mikhail Budyko, a Russian climatologist, developed a simple energy-balance climate model to investigate the effect of ice cover on global climate. Using this model, Budyko found that if ice sheets advanced far enough out of the polar regions, a feedback loop ensued where the increased reflectiveness (albedo) of the ice led to further cooling and the formation of more ice, until the entire Earth was covered in ice and stabilized in a new ice-covered equilibrium.[7] While Budyko's model showed that this ice-albedo stability could happen, he concluded that it had in fact never happened, because his model offered no way to escape from such a feedback loop. In 1971, Aron Faegre, an American physicist, showed that a similar energy-balance model predicted three stable global climates, one of which was snowball earth.[8] This model introduced Edward Norton Lorenz's concept of intransitivity indicating that there could be a major jump from one climate to another, including to snowball earth.
 
The term "snowball Earth" was coined by Joseph Kirschvink in a short paper published in 1992 within a lengthy volume concerning the biology of the Proterozoic eon.[9] The major contributions from this work were: (1) the recognition that the presence of banded iron formations is consistent with such a global glacial episode, and (2) the introduction of a mechanism by which to escape from a completely ice-covered Earth - specifically, the accumulation of CO2 from volcanic outgassing leading to an ultra-greenhouse effect.
 
Franklyn Van Houten's discovery of a consistent geological pattern in which lake levels rose and fell is now known as the "Van Houten cycle." His studies of phosphorus deposits and banded iron formations in sedimentary rocks made him an early adherent of the "snowball Earth" hypothesis postulating that the planet's surface froze more than 650 million years ago.[10]
 
Interest in the notion of a snowball Earth increased dramatically after Paul F. Hoffman and his co-workers applied Kirschvink's ideas to a succession of Neoproterozoic sedimentary rocks in Namibia and elaborated upon the hypothesis in the journal Science in 1998 by incorporating such observations as the occurrence of cap carbonates.[11]
 
In 2010, Francis MacDonald reported evidence that Pangaea was at equatorial latitude during the Cryogenian period with glacial ice at or below sea level, and that the associated Sturtian glaciation was global.[12][13]
 
Evidence[edit]
 
The snowball Earth hypothesis was originally devised to explain geological evidence for the apparent presence of glaciers at tropical latitudes.[14] According to modelling, an ice-albedo feedback would result in glacial ice rapidly advancing to the equator once the glaciers spread to within 25°[15] to 30°[16] of the equator. Therefore, the presence of glacial deposits within the tropics suggests global ice cover.
 
Critical to an assessment of the validity of the theory, therefore, is an understanding of the reliability and significance of the evidence that led to the belief that ice ever reached the tropics. This evidence must prove two things:
 
that a bed contains sedimentary structures that could have been created only by glacial activity;
 
that the bed lay within the tropics when it was deposited.
 
During a period of global glaciation, it must also be demonstrated that glaciers were active at different global locations at the same time, and that no other deposits of the same age are in existence.
 
This last point is very difficult to prove. Before the Ediacaran, the biostratigraphic markers usually used to correlate rocks are absent; therefore there is no way to prove that rocks in different places across the globe were deposited at precisely the same time. The best that can be done is to estimate the age of the rocks using radiometric methods, which are rarely accurate to better than a million years or so.[17]
 
The first two points are often the source of contention on a case-to-case basis. Many glacial features can also be created by non-glacial means, and estimating the approximate latitudes of landmasses even as recently as 200 million years ago can be riddled with difficulties.[18]
 
Palaeomagnetism[edit]
 
The snowball Earth hypothesis was first posited to explain what were then considered to be glacial deposits near the equator. Since tectonic plates move slowly over time, ascertaining their position at a given point in Earth's long history is not easy. In addition to considerations of how the recognizable landmasses could have fit together, the latitude at which a rock was deposited can be constrained by palaeomagnetism.
 
When sedimentary rocks form, magnetic minerals within them tend to align themselves with the Earth's magnetic field. Through the precise measurement of this palaeomagnetism, it is possible to estimate the latitude (but not the longitude) where the rock matrix was formed. Palaeomagnetic measurements have indicated that some sediments of glacial origin in the Neoproterozoic rock record were deposited within 10 degrees of the equator,[19] although the accuracy of this reconstruction is in question.[17] This palaeomagnetic location of apparently glacial sediments (such as dropstones) has been taken to suggest that glaciers extended from land to sea level in tropical latitudes at the time the sediments were deposited. It is not clear whether this implies a global glaciation, or the existence of localized, possibly land-locked, glacial regimes.[20] Others have even suggested that most data do not constrain any glacial deposits to within 25° of the equator.[21]
 
Skeptics suggest that the palaeomagnetic data could be corrupted if Earth's ancient magnetic field was substantially different from today's. Depending on the rate of cooling of Earth's core, it is possible that during the Proterozoic, the magnetic field did not approximate a simple dipolar distribution, with north and south magnetic poles roughly aligning with the planet's axis as they do today. Instead, a hotter core may have circulated more vigorously and given rise to 4, 8 or more poles. Palaeomagnetic data would then have to be re-interpreted, as the sedimentary minerals could have aligned pointing to a 'West Pole' rather than the North Pole. Alternatively, Earth's dipolar field could have been oriented such that the poles were close to the equator. This hypothesis has been posited to explain the extraordinarily rapid motion of the magnetic poles implied by the Ediacaran palaeomagnetic record; the alleged motion of the north pole would occur around the same time as the Gaskiers glaciation.[22]
 
CONTINUED AT 
 
 

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#9 grog

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Posted 19 September 2017 - 11:31 AM

"Snowball Earth" Confirmed: Ice Covered Equator 
 
 
 
 
5 MARCH 2010.
 
 
 
 
But volcanoes would've made Earth more mud ball than snowball, scientists say.
 
Maroon iron-rich glacial deposits at peak overlying and grey carbonate reef in the Ogilvie
 
Mountains of the Yukon Territory. 
 
VIEW IMAGES
 
Maroon glacial-deposit layers helped prove this Canadian rock was ice covered and at the Equator during the "snowball Earth" period. 
 
PHOTOGRAPH COURTESY FRANCIS A. MACDONALD
 
Earth's now steamy Equator was covered with ice 716 million years ago, according to a new study.
 
The finding appears to add solid evidence to the theory of an ancient "snowball Earth."
 
The discovery hinged on proving that the right rocks had been covered by glaciers in the right place at the right time.
 
Study leader Francis Macdonald, an Earth scientist at Harvard University, and colleagues worked with volcanic rocks in Canada that were found sandwiched between glacial deposits. Such deposits are recognizable by the presence of debris left behind by melting glaciers and sediments deformed by glacial movement.
 
Using extremely precise uranium-lead mass spectrometry, the researchers determined that both the volcanic rocks and glacial sediments were deposited about 716.5 million years ago-during the purported snowball-Earth period.
 
The team then matched their findings to previous magnetic studies that had found these rocks had formed when Canada was situated near the Equator.
 
Over time the movement of Earth's tectonic plates had pushed the rocks north to Canada's Yukon and Northwest Territories.
 
Snowball Earth or Mud-ball Earth?
 
There's still plenty of mystery surrounding snowball Earth-aka the Sturtian glaciation-Macdonald said.
 
For example, an icy Equator alone can't tell scientists the extent of ice cover around the world. The continents may have been in a total deep freeze, or the planet may have simply been subjected to a patchwork of constantly moving glaciers or icebergs-or something in between.
 
And even the "snowball Earth" name might need rethinking.
 
Earth probably wasn't "just a white ball, but more of a mud ball," Macdonald said. Regular eruptions of ash-spewing volcanoes likely made the continents "dusty messes."
 
Since plants had not yet evolved 700 million years ago, the dirty ice could have been the only dark spots on Earth's surface to absorb the sun's rays. As a result, these regions may have been more likely to melt, creating water bodies where primitive life-forms, such as algae and fungi, could thrive.
 
That some organisms survived-and even branched off into new species-during the Sturtian glaciation adds credence to the idea that snowball Earth harbored open-water refuges, or at least cracks in the ice, Macdonald said.
 
For instance, modern-day ice cracks off Antarctica are "chockablock" with single-celled life-forms, he said.
 
(Also see "Did Plants Cool the Earth and Spark Explosion of Life?")
 
Global Warming Insights
 
Learning about Earth's past extremes may also give scientists new perspectives on modern climate change.
 
For instance, scientists know that over the millennia our planet has yo-yoed between pervasive ice cover and hothouse conditions such as those during the ice-free, dinosaur-packed Cretaceous period, said Macdonald, whose study appears tomorrow in the journal Science (prehistoric time line).
 
"This is just all to say that Earth is sensitive, and we can get perturbations that can lead to a different world," he said.
 
For instance, eruptions during the snowball-Earth period are thought to have added sulfur particles to the atmosphere, blocking sunlight and cooling the planet. Some experts have suggested doing the same thing artificially as a modern cure for global warming.
 
That means investigating such "natural experiments" in Earth's history is crucial, Macdonald said. "That's going to tell us a lot more than any little [computer] model can say."
 
 

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#10 grog

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Posted 19 September 2017 - 11:39 AM

Scientists State: Advanced Alien Civilizations DID Exist Before Us
 
 
 
 
 
 
 
It seems that after all, we may not bee the only intelligent civilization in the known universe.
 
In 1961, astrophysicist Frank Drake came up with an equation that calculates the number of advanced civilizations likely to exist in the Milky Way galaxy. Today, researchers have remodeled the equation using new data from the Kepler satellite. The results are fascinating.drank-equation
 
Scientists have concluded that human beings aren't the only intelligent civilization in the universe after a recent revision of the famous Drake Equation of 1961. The equation estimates the number of potential intelligent civilizations in the universe.
 
Scientists adapted the Drake Equation with data from NASA's Kepler satellite on habitable planets in the cosmos. Researchers modified the Drake Equation from detailing the number of extraterrestrial civilizations that exist now, to about the chance of our civilization being the only one ever existed.
 
The new research indicates that unless the odds of intelligent lifeforms evolving on habitable planets are extremely low,  life on Earth is not the only one that evolved to an advanced stage.
 
Scientists explain that the chance of an advanced civilization developing would need to be less tan one in 10 trillion, for our civilization to be the only intelligent one in the known universe.
 
However, data obtained from Kepler changes everything placing the odds at a much higher percentage, meaning that technologically advanced civilizations are likely to have evolved at a certain point in the life of the universe.
 
A New Empirical Constraint on the Prevalence of Technological Species in the Universe
 
Researchers turned to the specific question, ''Has even one other technological species ever existed in the observable Universe?''
 
Adam Frank, professor of physics and astronomy at the University of Rochester and co-author of the paper stated that: 'The question of whether advanced civilizations exist elsewhere in the universe has always been vexed with three significant uncertainties in the Drake equation.
 
'We've known for a long time approximately how many stars exist.
 
'We didn't know how many of those stars had planets that could potentially harbor life, how often life might evolve and lead to intelligent beings, and how long any civilizations might last before becoming extinct.'
 
'Thanks to Nasa's Kepler satellite and other searches, we now know that roughly one-fifth of stars have planets in 'habitable zones,' where temperatures could support life as we know it.
 
'So one of the three big uncertainties has now been constrained.'
 
However, a question that remains a puzzle is how long civilizations might have survived.
 
'The fact that humans have had rudimentary technology for roughly ten thousand years doesn't really tell us if other societies would last that long or perhaps much longer,' he explained.
 
However, authors of the study Frank and Woodruff Sullivan of the astronomy department at the University of Washington discovered that they could eliminate that term altogether by simply expanding the question.
 
"Rather than asking how many civilizations may exist now, we ask 'Are we the only technological species that has ever arisen?" said Sullivan. "This shifted focus eliminates the uncertainty of the civilization lifetime question and allows us to address what we call the 'cosmic archeological question'-how often in the history of the universe has life evolved to an advanced state?" (source)
 
Frank and Sullivan mixed things up, refreshing the Drake equation. Instead of taking a guess at the odds of intelligent life developing, they calculated the change against it occurring for humanity to be the only known advanced civilization out there. Researchers calculated the chance between a universe where mankind has been the sole experiment in civilization and another one where other advanced civilizations might have developed before the rise of advanced lifeforms on earth.
 
"Of course, we have no idea how likely it is that an intelligent technological species will evolve on a given habitable planet," says Frank. But using our method we can tell exactly how low that probability would have to be for us to be the ONLY civilization the Universe has produced. We call that the pessimism line. If the actual probability is greater than the pessimism line, then a technological species and civilization have likely happened before." (source)
 
Sullivan and Frank calculated how unlikely would it be for advanced life to exist if there has never been another one developing somewhere in the ten billion trillion stars in the universe or even among our own galaxy's hundred billion stars. This approach changed the way we look at the Drake equation and the likelihood we are alone in the universe.
 
"One in 10 billion trillion is incredibly small," says Frank. "To me, this implies that other intelligent, technology producing species very likely have evolved before us. Think of it this way. Before our result, you'd be considered a pessimist if you imagined the probability of evolving a civilization on a habitable planet were, say, one in a trillion. But even that guess, one chance in a trillion, implies that what has happened here on Earth with humanity has in fact happened about a 10 billion other times over cosmic history!" (source)
 
However, on a smaller scale, the universe are less extreme. Researchers speculate that another technologically advanced species likely evolved on a habitable planet in our galaxy if the odds against it are better than one chance in 60 billion.
 
"The universe is more than 13 billion years old," said Sullivan. "That means that even if there have been a thousand civilizations in our own galaxy if they live only as long as we have been around-roughly ten thousand years-then all of them are likely already extinct. And others won't evolve until we are long gone. For us to have much chance of success in finding another "contemporary" active technological civilization, on average they must last much longer than our present lifetime."
 
"Given the vast distances between stars and the fixed speed of light we might never really be able to have a conversation with another civilization anyway," said Frank. "If they were 20,000 light years away, then every exchange would take 40,000 years to go back and forth." (source)
 
Franck and Sullivan point out in their revolutionary study that even though there aren't other advanced civilizations in the Milky way, the results of the study have a profound scientific and philosophical meaning.

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#11 grog

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Posted 19 September 2017 - 11:44 AM

Reversals: Magnetic Flip
 
 
 
 
04 December 2016.
 
 
 
 
What do we mean by a magnetic reversal or a magnetic 'flip' of the Earth?
 
How often do reversals occur?
 
Is the Earth's magnetic field reversing now? How do we know?
 
How quickly do the poles 'flip'?
 
What happens during a reversal? What do we see at the Earth's surface?
 
Is there any danger to life?
 
I'm interested in a more technical description. Can you tell me more?
 
Links to other descriptions of the Earth's magnetic field.
 
What do we mean by a magnetic reversal or a magnetic 'flip' of the Earth?
 
The Earth has a magnetic field, as can be seen by using a magnetic compass. It is mainly generated in the very hot molten core of the planet and has probably existed throughout most of the Earth's lifetime. The magnetic field is largely that of a dipole, by which we mean that it has one North pole and one South pole. At these places, a compass needle will point straight down, or up, respectively. It is often described as being similar in nature to the field of a bar (e.g. fridge) magnet. However there is much small-scale variation in the Earth's field, which is quite different from that of a bar magnet. In any event, we can say that there are currently two poles observed on the surface of the Earth, one in the Northern hemisphere and one in the Southern hemisphere.
 
By magnetic reversal, or 'flip', we mean the process by which the North pole is transformed into a South pole and the South pole becomes a North pole. Interestingly, the magnetic field may sometimes only undergo an 'excursion', rather than a reversal. Here, it suffers a large decrease in its overall strength, that is, the force that moves the compass needle. During an excursion the field does not reverse, but later regenerates itself with the same polarity, that is, North remains North and South remains South.
 
Back to the top.
 
How often do reversals occur?
 
As a matter of geological record, the Earth's magnetic field has undergone numerous reversals of polarity. We can see this in the magnetic patterns found in volcanic rocks, especially those recovered from the ocean floors. In the last 10 million years, there have been, on average, 4 or 5 reversals per million years. At other times in Earth's history, for example during the Cretaceous era, there have been much longer periods when no reversals occurred. Reversals are not predictable and are certainly not periodic in nature. Hence we can only speak about the average reversal interval.
 
Back to the top.
 
Is the Earth's magnetic field reversing now? How do we know?
 
Measurements have been made of the Earth's magnetic field more or less continuously since about 1840. Some measurements even go back to the 1500s, for example at Greenwich in London. If we look at the trend in the strength of the magnetic field over this time (for example the so-called 'dipole moment' shown in the graph below) we can see a downward trend. Indeed projecting this forward in time would suggest zero dipole moment in about 1500-1600 years time. This is one reason why some people believe the field may be in the early stages of a reversal. We also know from studies of the magnetisation of minerals in ancient clay pots that the Earth's magnetic field was approximately twice as strong in Roman times as it is now.
 
Dipole moment 1850-2020 from 2 models
 
Even so, the current strength of the magnetic field is not particularly low in terms of the range of values it has had over the last 50,000 years and it is nearly 800,000 years since the last reversal. Also, bearing in mind what we said about 'excursions' above, and knowing what we do about the properties of mathematical models of the magnetic field, it is far from clear we can easily extrapolate to 1500 years hence.
 
Back to the top.
 
How quickly do the poles 'flip'?
 
We have no complete record of the history of any reversal, so any claims we can make are mostly on the basis of mathematical models of the field behaviour and partly on limited evidence from rocks that retain an imprint of the ancient magnetic field present when they were formed. For example, the mathematical simulations seem to suggest that a full reversal may take about one to several thousand years to complete. This is fast by geological standards but slow on a human time scale.
 
Back to the top.
 
What happens during a reversal? What do we see at the Earth's surface?
 
As above, we have limited evidence from geological measurements about the patterns of change in the magnetic field during a reversal. We might expect to see, based on models of the field run on supercomputers, a far more complicated field pattern at the Earth's surface, with perhaps more than one North and South pole at any given time. We might also see the poles 'wandering' with time from their current positions towards and across the equator. The overall strength of the field, anywhere on the Earth, may be no more than a tenth of its strength now.
 
Back to the top.
 
Is there any danger to life?
 
Almost certainly not. The Earth's magnetic field is contained within a region of space, known as the magnetosphere, by the action of the solar wind. The magnetosphere deflects many, but not all, of the high-energy particles that flow from the Sun in the solar wind and from other sources in the galaxy. Sometimes the Sun is particularly active, for example when there are many sunspots, and it may send clouds of high-energy particles in the direction of the Earth. During such solar 'flares' and 'coronal mass ejections', astronauts in Earth orbit may need extra shelter to avoid higher doses of radiation. Therefore we know that the Earth's magnetic field offers only some, rather than complete, resistance to particle radiation from space. Indeed high-energy particles can actually be accelerated within the magnetosphere.
 
At the Earth's surface, the atmosphere acts as an extra blanket to stop all but the most energetic of the solar and galactic radiation. In the absence of a magnetic field, the atmosphere would still stop most of the radiation. Indeed the atmosphere shields us from high-energy radiation as effectively as a concrete layer some 13 feet thick.
 
Human beings and their ancestors have been on the Earth for a number of million years, during which there have been many reversals, and there is no obvious correlation between human development and reversals. Similarly, reversal patterns do not match patterns in species extinction during geological history.
 
Some animals, such as pigeons and whales, may use the Earth's magnetic field for direction finding. Assuming that a reversal takes a number of thousand years, that is, over many generations of each species, each animal may well adapt to the changing magnetic environment, or develop different methods of navigation.
 
Back to the top.
 
I'm interested in a more technical description. Can you tell me more?
 
The source of the magnetic field is the iron-rich liquid outer core of the Earth. This liquid moves in complex ways as a result of the convection of the heat deep within the core and of the rotation of the planet. The motion of the core fluid is continuous and never stops, even during a reversal. It can only stop when the energy source fails. Heat is produced at least partly because of the solidification of the liquid core onto the solid inner core that sits at the centre of the Earth. This process has operated continuously over billions of years. At the top of the liquid core, some 3000 km beneath our feet and below the rocky mantle, the fluid may travel at horizontal speeds of tens of kilometres per year. The motion of this metal fluid across existing magnetic field lines of force produces electrical currents and these, in turn, generate more magnetic field. This is a process known as advection. To balance any growth of the field, and thus stabilise what we call the 'geodynamo', we need diffusion, where field 'leaks' away from the core and is destroyed. Ultimately, the core fluid flow produces a complicated magnetic field pattern at the Earth's surface with a complicated time variation.
 
Simulations of the geodynamo on supercomputers have demonstrated the complex nature of the field and its behaviour over time. Simulations have also revealed reversals in the polarity, where the magnetic North pole is replaced by a South pole, and vice versa. In such simulations, the strength of the main dipole appears to weaken, perhaps to about 10% of its normal value (but not vanish) and the existing poles may wander across the globe and be joined by other temporary North and South magnetic poles (the 'non-dipole field').
 
The solid iron inner core of the Earth has been shown in these simulations to be important in controlling the reversal process. Because it is a solid, the inner core can't generate magnetic field by advection, but any field that is generated in the fluid outer core can diffuse, or spread, into the inner core. The field generation process (advection) in the outer core seems to regularly attempt to reverse. But unless the field locked into the inner core first diffuses away, a true reversed field cannot become established throughout the core. Essentially the inner core resists any 'new' field diffusing in and perhaps only one in every ten such reversal attempts is successful.
 
CONTINUED AT 
 
 
 

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#12 grog

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Posted 19 September 2017 - 11:47 AM

Odds Are Less Than 1 in 10 BILLION TRILLION That We The First Advanced Civilization!
 
 
 
 
 
June 14, 2016
 
 
 
A New York Times article, by Adam Frank, published in the Sunday Review points out that "the Odds Are Less One in 10 BILLION TRILLION That We Are Not The First" advanced civilizations, and that the possibility of communicating with extraterrestrials and proving the the existence of an alien society can be viewed with the aid of the "Drake Equation". Here are excerpts from Frank's outstanding article.
 
"LAST month astronomers from the Kepler spacecraft team announced the discovery of 1,284 new planets, all orbiting stars outside our solar system. The total number of such "exoplanets" confirmed via Kepler and other methods now stands at more than 3,000.
 
This represents a revolution in planetary knowledge. A decade or so ago the discovery of even a single new exoplanet was big news. Not anymore. Improvements in astronomical observation technology have moved us from retail to wholesale planet discovery. We now know, for example, that every star in the sky likely hosts at least one planet.
 
But planets are only the beginning of the story. What everyone wants to know is whether any of these worlds has aliens living on it. Does our newfound knowledge of planets bring us any closer to answering that question?
 
A little bit, actually, yes. In a paper published in the May issue of the journal Astrobiology, the astronomer Woodruff Sullivan and I show that while we do not know if any advanced extraterrestrial civilizations currently exist in our galaxy, we now have enough information to conclude that they almost certainly existed at some point in cosmic history.
 
Among scientists, the probability of the existence of an alien society with which we might make contact is discussed in terms of something called the Drake equation. In 1961, the National Academy of Sciences asked the astronomer Frank Drake to host a scientific meeting on the possibilities of "interstellar communication." Since the odds of contact with alien life depended on how many advanced extraterrestrial civilizations existed in the galaxy, Drake identified seven factors on which that number would depend, and incorporated them into an equation.
 
You might assume this probability is low, and thus the chances remain small that another technological civilization arose. But what our calculation revealed is that even if this probability is assumed to be extremely low, the odds that we are not the first technological civilization are actually high. Specifically, unless the probability for evolving a civilization on a habitable-zone planet is less than one in 10 billion trillion, then we are not the first.
 
To give some context for that figure: In previous discussions of the Drake equation, a probability for civilizations to form of one in 10 billion per planet was considered highly pessimistic. According to our finding, even if you grant that level of pessimism, a trillion civilizations still would have appeared over the course of cosmic history.
 
In other words, given what we now know about the number and orbital positions of the galaxy's planets, the degree of pessimism required to doubt the existence, at some point in time, of an advanced extraterrestrial civilization borders on the irrational.
 
In science an important step forward can be finding a question that can be answered with the data at hand. Our paper did just this. As for the big question - whether any other civilizations currently exist - we may have to wait a long while for relevant data. But we should not underestimate how far we have come in a short time."

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#13 grog

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Posted 19 September 2017 - 12:18 PM

Like nothing on Earth: An 'impossible' crystal is discovered in Siberia after crashing to our planet in a meteorite
 
 
 
 
09 December 2016.
 
 
 
 
 
Researchers have discovered the third ever naturally formed quasicrystal 
 
It was identified from a tiny sample of meteorite found in Siberia in 2011
 
A quasicrystal's atoms can be arranged in ways not found in normal crystal
 
For years researchers believed quasicrystals could only be made artificially
 
 
 
 
An incredibly rare and unusual type of crystal, once dismissed as impossible to exist, has been identified on a piece of meteorite in Russia.
 
With a strange repeating structure, for years researchers believed quasicrystals could only be made artificially.
 
Now the discovery, published in a new paper, marks the third finding of the bizarre materials in their natural form.
 
An incredibly rare and unusual type of crystal, once dismissed as impossible to exist, has been identified on a piece of meteorite in Russia .The discovery, published in a new paper, marks the third finding of the bizarre materials in their natural form +6
 
An incredibly rare and unusual type of crystal, once dismissed as impossible to exist, has been identified on a piece of meteorite in Russia .The discovery, published in a new paper, marks the third finding of the bizarre materials in their natural form
 
 
 
 
A HISTORY OF QUASICRYSTALS 
 
With a strange and irregular structure, for years researchers believed quasicrystals could only be made artificially.
 
Researchers discovered the first naturally formed quasicrystals in the early 2000s, after years of manufacturing artificial samples.
 
Princeton physicist Paul Steinhardt and colleague Luca Bindi, from the University of Florence, found a grain of an aluminium, copper, and iron mineral with five-fold symmetry.
 
In 2015, Steinhardt and his team found a second quasicrystal. 
 
Now, sixteen years later, the third specimen has been identified. 
 
 
 
 
The crystal, identified in a new paper published in Scientific Reports, was analysed by researchers at the University of Florence, Caltech and Princeton.
 
The material came from a meteorite found in the Khatyrka region of the Russian far east five years ago.
 
The team found a tiny sample of quasicrystal, just a few micrometres wide, after scanning the meteorite using scanning electron microscopy.
 
The two examples of natural quasicrystal found previously were taken from the same meteorite, but were different patterns. 
 
The latest version features a kind of symmetry not seen naturally before, called icosahedral symmetry. 
 
This an exotic pattern featuring 60 points of rotational symmetry, made up of aluminium, copper and iron. 
 
'What is encouraging is that we have already found three different types of quasicrystals in the same meteorite, and this new one has a chemical composition that has never been seen for a quasicrystal,' co-author Paul Steinhardt from Princeton University, told Motherboard. 
 
 

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#14 grog

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Posted 19 September 2017 - 12:29 PM

Life on Other Planets?
 
 
 
 
Given the abundance of life on Earth and the immensity of the known universe, what is the possibility of life on other planets? This question is fun to think about. Consider this possibility just for our Milky Way galaxy, one of an estimated hundred billion galaxies that make up the known universe. Within this galaxy, our Sun is one of one hundred billion-plus stars. That's one hundred billion other suns, each with the potential to have solar systems of its own; but, to the conservative, let's imagine that only one half of those suns in our galaxy actually have planets. This leaves us with roughly ?fty billion suns, each with planets, in the Milky Way galaxy.
 
However, planets with the characteristics that make them candidates for life-just the right distance from their sun and just the right size for the formation of a life-sustaining atm0sphere-might be relatively rare. Thus, let's be conservative again and grant that only one in every ?ve hundred of those ?fty billion suns in our galaxy has a planet with the basic characteristics required for life as we know it. This still leaves us with roughly a hundred million planets with the potential for life support in just our galaxy.
 
With the possibility of extraterrestrial life seemingly all around us, perhaps a more appropriate question is: Why haven't we had any visitors? Or if we are having visitations, why aren't they more common? The reason, in large part, may be the extreme size of our galaxy. The average distance between stars, considering all stars, is ?ve hundred light years. And how big is that? Well, one light year is the distance that light, moving at the speed of 186,000 miles per second, travels in one year. And how far is that? Let's do the math: 186,000 miles/second X 60 seconds/minute x 60 minutes/hour X 24 hours/day X 365 days/year = 5,865,696,000,000 miles/year. Yes, one light year is approximately six trillion miles-a colossal distance-and the average distance between stars is not one light year, but ?ve hundred light years! And, of course, the average distance between that particular subset of stars with potentially life-supporting planets would be even greater. In addition to these vast distances in space, we also have "distance" in time-that is, possible civilizations would be scattered in time.
 
To grasp this concept, consider that our solar system has been around for almost ?ve billion years, but intelligent life (e.g., us), capable of reaching out into space, has been in existence for only a very, very tiny fraction of that time. Thus, at any one time, we may only have a few thousand stars in our galaxy simultaneously supporting a planet with life; and the average distance between these stars, given the size of the Milky Way, would likely be on the order of thousands of light years. None of this rules out the possibility that there could be extraterrestrial beings in our galaxy that are unimaginably more complex, intelligent, and marvelous than we are-beings that perhaps have already checked us out and concluded that we are not very interesting given our primitive state. It is a humbling thought.

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#15 grog

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Posted 19 September 2017 - 12:34 PM

 
 
 
 
 
 
Is There Life on Other Planets?
 
Most of us, at some point in life, must have pondered over the eternal query of the existence of life on other planets. Are we the only ones in the depths of this endless ocean called the Universe? Read this Buzzle article to know more about the endless list of possibilities that reside somewhere in the corners of our imagination.
 
Martian Microbes
 
The meteorite named ALH84001 impacted the Earth in present-day Antarctica more than 15 million years ago. An extensive study of this specimen reveals that the components contain structures, which appear more or less like bacteria or other similar microscopic organisms. Such potential bacteria-like microbes must have fossilized in the meteorite during its formation. This further strengthens the argument that millions of years ago, life did exist on Mars!
 
Extraterrestrial life has always been the subject of human expressions in various forms like movies, paintings, or popular stories. This topic has been a subject of intense debate, not only among the common people, but also among the intellectuals around the world. However, one fact clearly stands tall; there is no proof till date that can conclusively state or authenticate the presence of a life form other than that on Earth. Even though there is no evidence, the possibility of a civilization existing somewhere out there may be worth considering. Crop circles, another phenomenon that has benumbed humans, is thought to have been influenced by the aliens.
 
5 Controversial Theories of Life on Other Planets
 
Drake Equation Theory
 
? In 1961, US astronomer Frank Drake had developed an equation that suggested the presence of many more life-bearing planets, and the possibility of an alien life form that can communicate. The equation includes several factors like the age and formation of stars, number of Earth-like planets, probability of communication, etc. Initially, this method garnered much attention, as the statistics produced were quite plausible, but later on, as numerous space systems were studied, the calculation started becoming more complex, ultimately producing results that vary a lot.
 
? The different components of the equation given above can be explained in a very simple, yet effective format. Out of all the components, the mean rate of star formation R* has been calculated approximately till now, which indicates that about four new stars are born at least in our galaxy, the Milky Way, every year. The other factors can only be assumed or guessed, depending on the level of research.
 
? In a typical galaxy, only a quarter of all the stars are included in solar systems. These formations have at least two planets that can be potentially inhabitable. The components of development of life, evolution of intelligence, and the ability to be technologically superior might develop at a chance of 50% on such planets. If at all a civilization or a race evolves, it might attempt communication in around 4,000,000 years. Thus, putting all these factors in the formula, the equation becomes:
 
NT = 4*0.25*2*0.5*0.5*0.5*4,000,000
 
= 1,000,000
 
Thus, the number of potential civilizations that are still undiscovered is about a million, which may attempt contact in the near future. But, on a more practical scenario, the existence of different planets that can harbor such a number of forms is very rare and remote.
 
? The complexity arises from the fact that there are countless factors and parameters that must operate before a life form actually emerges and evolves. If all the variables are summed up, they can stated as: combination of various inorganic molecules that remained in a residual form or a part of the primordial soup (a term that explains the state of matter after the Big Bang), formation of organic molecules that from the inorganic ones, the existence of a star like the Sun that will provide energy for biochemical reactions to take place, change in conditions that are suitable for unicellular life, extreme obstacles that have to be overcome in order that multicellular life becomes successful, etc. As living proof, all the organisms, whether unicellular or multicellullar, primitive or advanced, have passed through these various stages described above.
 
Panspermia Theory
 
? The term 'panspermia' has a Greek origin that means 'seeds everywhere'. According to this theory, life was 'seeded' on Earth from outer space, i.e., life was brought to our planet from a foreign space body. Such bodies could have been comets, meteors, or even asteroids that caused an impact on our planet. Mostly, the organisms were in the form of microbes, as multicellular life did not exist millions of years ago. Thus, if life did not first originate on Earth, did it flourish on other planets, before the Earth was even born? If abiogenesis (the process of appearance of life) is possible on Earth, can it take place even on other planets?
 
? The answers to such questions can be attempted with the help of this theory that was proposed in 1973 in its modern form by two people: a physicist called Francis Crick and a chemist called Leslie Orgel. The theory in its crude form was first mentioned around 450 BCE by a Greek philosopher called Anaxagoras. There are three subtypes of the panspermia concept that explain the origin of life.
 
Directed Panspermia
 
According to this concept, highly advanced civilizations that are more developed than us do exist on planets that are close to our world. These civilizations would have intentionally or accidentally spread the biochemical structure to our planet, during its early stages of formation. Though more or less improbable and a bit fictitious, this concept is nevertheless possible.
 
Ballistic Panspermia
 
The spreading of life forms from one planetary body to another that are present in the same solar system is called ballistic panspermia. This concept is widely used to explain and debate that life on Earth in fact originated due to seeding from Mars, which was possibly inhabited by alien life forms millions of years ago.
 
Lithopanspermia
 
One of the most difficult processes, lithopanspermia refers to the seeding of biochemical forms on another planet that is present in a different solar system, as compared to the system from where the spreading medium belongs to. The DNA molecules have to survive the harsh conditions of outer space before reaching the particular celestial body.
 
? Although the panspermia concept has garnered much attention in recent years, it does not explain a few points.
 
A major one is that if life existed on Mars before Earth, where is it now? If it got extinct, then suitable fossil appearances should have been found till now by the three robotic rovers on the red planet.
 
Also, if a more advanced civilization spread the biomolecules to our planet, why didn't they contact us, i.e., humans, again after our planet underwent significant changes regarding evolution and development of higher life forms?
 
Such questions might be answered if we ever find aliens on another planet.
 
Biochemical Evolution Theory
 
? The most important factor in determining the presence of life is the environment. If we assume that the conditions such as those on planet Earth can be created anywhere in the Universe or already exist in it, then the idea of life on that planet is almost a certainty. Based on the survival mechanism of human beings, we may be able to predict the possibility of a whole new set of beings similar to us.
 
? Human beings need air to breathe, water to drink, and food for survival. The availability of these factors is a must for each one of us to sustain on Earth. Hence, there is a lot of curiosity among experts with regard to the planet Mars, Mercury, Jupiter, the moons of Jupiter and Saturn like Europa and Titan, respectively, in our solar system. These have been found to have traces of water on their surface. Therefore, there is every chance that life will be able to thrive on these bodies.
 
? The interaction between inorganic compounds gives rise to organic molecules like proteins, amino acids, carbohydrates, lipids, etc. For such processes to take place, the availability of liquid water is essential. On our planet, the appearance of unicellular forms and the subsequent multicellular organisms too, first took place in the oceans. Moons like Titan, Europa, Enceladus, etc., are being said to consist of oceans underneath their solid surfaces. These bodies particularly might contain methane (CH4), which plays a crucial role in the development of primitive life forms. Thus, the chances of finding extraterrestrial microbes on such moons are quite high, though the occurrence of complex life forms in our own solar system is not detected as of today.
 
? The 1976 Viking probes sent to planet Mars had detected chemical activity, which was quite similar to the daily activity of living organisms on Earth. NASA had conducted detailed analysis of the samples collected by the probes and closed the speculation, citing lack of concrete results. In 2001, another updated theory based on a complex set of equations suggested the presence of many planets that could sustain life. Jupiter's moon Europa radiates infrared waves, which is typical of an organism such as bacteria. Hence, it is subject to a very intense scrutiny and observation by NASA, but substantial evidence still eludes us. However, all the above incidents have encouraged a lot of interest and a renewed effort by researchers all over the world to settle the claims of life on other planets once and for all.
 
Theory of Extremophiles
 
? The organisms (mostly microbes) that can survive the most harsh conditions ever present on our planet, as well as in the outer space are called extremophiles. These life forms are seen on our planet, where extreme conditions are present. Extremophiles are known to exist below the Antarctic ice sheets, near volcanic fumaroles and vents, underwater volcanoes and hot spots, the Earth's exosphere, etc. Some examples of such organisms are: Tardigrades, Chernobyl Fungus, Pompeii Worm, etc. Few multicellular and bioluminescent organisms also exist only at great depths in the ocean, where sunlight cannot penetrate.
 
? Some planets and even moons also exhibit such harsh conditions, though exact replication is not present. According to expert study and astrobiological research, if the Earth can harbor such organisms under inhospitable parameters, such microbes might also be present on other planets, depending on the intensity of the specific aspect, where the microbes might be found. Such life forms also have to survive against the bombardment of cosmic rays, gamma rays, solar wind, etc. In 2013, a bacterium named Tersicoccus phoenicis was discovered in two regions of the world, one each in South America and the USA. This microbe was only found in the docking chambers of the spacecrafts and nowhere else. Till present, even after a year, extensive studies have been carried out in various regions on our planet, and this organism has not been found in any environment. Thus, it can be assumed that Tersicoccus phoenicis was carried by the spacecraft on entry in our atmosphere from the outer space onto our planet. This microbe may possibly thrive in the exosphere region, or even beyond in the space vacuum.
 
? Another experiment that is famous for proving this theory is the one where few scientists created surface and subsurface conditions that are similar those assumed to be present on the Europa moon of Jupiter. This moon was particularly chosen as it is the best candidate for the occurrence of marine or oceanic conditions below its surface. In the study, microbes like N. magadii and D. radiodurans were subjected to intense UV radiation. The results showed that most of them died, but few actually survived the onslaught of the UV rays. This indicates that Europa is a prime candidate for the thriving of microorganisms in its oceans, apart from our planet.
 
? The theory of extremophiles is the least credible one among all, as very little data has been obtained or is available with scientists. This subfield of astrobiology needs sufficient attention, if we continue our search of alien life on other celestial bodies.
 
Habitable Planet Theory
 
? Another theory assumes that there is a unique structure (as that of the Earth) that has got the right components to enable life to flourish. The discoveries until now have failed to conclusively prove the existence of conditions exactly similar to those on Earth. If we consider part of the Universe that we know, as a sample of the larger expanse, there might be no life at all. This is again just a probability based on the knowledge, which we have been able to garner till today.
 
? The Earth is placed in a habitable zone in our solar system, and this zone encompasses the space consisting of at least half of Venus and the whole of Earth and Mars. It extends a bit beyond the Martian orbit. The recently discovered planet called Gliese 581g is a potential example of a planet that exists in the habitable zone of its solar system. There are six planets including 581g that orbit a red star called Gliese 581. This body is more than 20 light years away from the Earth. Other examples of planets that exist within the habitable zones of their system are Kepler-186f and HD 40307g. These exist about 40 and 500 light years away from Earth, respectively. Every exoplanet discovered is first classified on the basis of its surface temperature, presence or absence of atmosphere, size, distance from its sun, composition, etc. Based on these factors, it is categorized to be under a non-habitable or a habitable zone.
 
? The presence of life beyond the solar system is a very contentious matter. There is a section of people who believe that on account of the expanse of the Universe, there must be a planet like Earth that supports life. The issue is a matter of research and speculation. The argument that there could be a planet like Earth, that exists in the realms of the Universe is a very likely event. Considering the sheer expanse of the Universe, we may be tempted to believe in the theory that there is a parallel civilization flourishing somewhere out in the cosmos. The only constraint facing us and perhaps the aliens is that both sides are unaware of a communication mechanism. We, humans, have come a long way since our evolution on this planet. But our achievements have not yet been able to make us aware of such an extraterrestrial being (if at all it exists). Similarly, if we again assume that a civilization does exist somewhere out there, even they have a long way to go and actually communicate with us.
 
The SETI (Search for Extraterrestrial Intelligence) Center located in Mountain View, California is dedicated to finding life in the Universe. This organization works in two broad areas: (i) research and development and (ii) projects. The first part includes development of new search techniques and equipment that would facilitate the search?for example, large telescopes and communication devices. The projects are the actual work directed with a well-planned strategy to search for the evidence of life. A lot of people claim to have seen an alien life form. The being is 'immortalized' in our memories by its depiction in various Hollywood movies, which leads us to firmly believe that there is life on other planets.
 
They say, "reality is more important than dreams", and all our assumptions and theories are still distant dreams created by our mind. The fact remains that so far we have not been able to detect life on other planets, but at the same time, there is no denying the possibility that it might actually exist!

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#16 grog

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Posted 19 September 2017 - 12:39 PM

Ice ages have been linked to the Earth's wobbly orbit - but when is the next one?
 
 
 
 
 
09 December 2016.
 
 
 
 
 
Over the last two and a half million years the Earth has undergone more than 50 major ice ages, each having a profound effect on our planet's climate. But what causes them and how do we predict when the next big ice age will hit?
 
About 40 years ago, scientists realised that ice ages were driven by changes in the Earth's orbit. But, as I recently argued in Nature, it's not that simple. Scientists are still trying to understand how such wobbles interact with the climate system, particularly greenhouse gases, to push the planet in to or out of an ice age.
 
During the last ice age, only 21,000 years ago, there was nearly continuous ice across North America from the Pacific to the Atlantic Ocean. At its deepest over the Hudson Bay, it was over two miles thick and reached as far south as what would now be New York and Cincinnati. In Europe, there were two major ice sheets: the British ice sheet which reached as far south as what would now be Norfolk, and the Scandinavian ice sheet that extended all the way from Norway to the Ural mountains in Russia.
 
In the Southern Hemisphere there were significant ice sheets on Patagonia, South Africa, southern Australia and New Zealand. So much water was locked up in these ice sheets that the global sea level dropped by over 125 metres - around ten metres lower than the height of the London Eye. In comparison if all the ice on Antarctica and Greenland melted today it would only raise sea level by 70 metres.
 
So what caused these great ice ages? In 1941, Milutin Milankovitch suggested that wobbles in the Earth's orbit changed the distribution of solar energy on the planet's surface, driving the ice age cycles. He believed that the amount of incoming solar radiation (insolation) just south of the Arctic Circle, at a latitude of 65°N, was essential. Here, insolation can vary by as much as 25%. When there was less insolation during the summer months, the average temperature would be slightly lower and some of the ice in this region could survive and build up - eventually producing an ice sheet.
 
But it wasn't until 30 years later that three scientists used long-term climate records from analysing marine sediments to put this to the test. Jim Hays used fossil assemblages to estimate past sea surface temperatures. Nick Shackleton calculated changes in past global ice volume by measuring oxygen isotopes (atoms with different numbers of neutrons in the nuclues) in calcium carbon fossil in marine sediments. John Imbrie used time-series analysis to statistically compare the timing and cycles in the sea surface temperature and global ice volume records with patterns of the Earth's orbit.
 
In December 1976 they published a landmark climate paper in Science, showing that climate records contained the same cycles as the three parameters that vary the Earth's orbit: eccentricity, obliquity and precession (shown in Figure 1). Eccentricity describes the shape of the Earth's orbit around the sun, varying from nearly a circle to an ellipse with a period of about 96,000 years. Obliquity is the tilt of the Earth's axis of rotation with respect to the plane of its orbit, which changes with a period of about 41,000 years. Precession refers to the fact that both Earth's rotational axis and orbital path precess (rotate) over time - the combined effects of these two components and the eccentricity produce an approximately 21,000-year cycle.
 
Figure 1. Author provided
 
The researchers also found that these parameters have different effects at different places on our globe. Obliquity has a strong influence at high latitudes, whereas precession has a notable impact on tropical seasons. For example precession has been linked to the rise and fall of the African rift valley lakes and so may have even influenced the evolution of our ancestors. Evidence for such "orbital forcing" of climate has now been found as far back as 1.4 billion years ago.
 
Beyond wobbles
 
However, the scientists realised that there were limitations and challenges of their research - many of which remain today. In particular, they recognised that variations in the Earth's orbit did not cause the ice age cycles per se - they rather paced them. A certain orbit of the Earth can be associated with many different climates. The one we have today is in fact similar to the one we had during the most intense part of the last ice age.
 
Small changes in insolation driven by changes in the Earth's orbit can push the planet into or out of an ice age through the planet's "climate feedback" mechanisms. For example when summer solar radiation in reduced it allows some ice to remain after the winter. This white ice reflects more sunlight, which cools the area further and allows more ice to build up, which reflects even more sunlight and so forth. Therefore, the researchers' next step was to understand the relative importance of ice sheet, ocean and atmospheric feedbacks. They discovered that greenhouse gases had an important role in controlling climate. In particular atmospheric carbon dioxide had to be low enough for the planet to start cooling before it could tip into an ice age.
 
So how can all this help us understand future climate? One idea is that small increases in greenhouse gases due to the expansion of agriculture that started 8,000 years ago have in fact delayed the next ice age. What's more, if we continue emitting greenhouse gases at the same rate, we might have put off the next ice age for at least half a million years.
 
If we have merely delayed the next ice age, we will still be in the Quaternary Period - the last 2.58m years defined by the ice age cycles. But if we have stopped the ice ages, humans will have caused a much greater change and so have entered the Anthropocene period as some argue. If I had to put money on it, I'd say the Earth has experienced its last ice age for a very, very long time.
 
 

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#17 grog

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Posted 19 September 2017 - 12:57 PM

Greenland's Vast Ice Sheet Is Way Less Stable Than We Thought, And That's Bad News For The World
 
 
 
 
09 December 2016.
 
 
 
 
 
Two new studies reveal just how dynamic - and potentially vulnerable to climate change - it actually is.
 
An iceberg detached from the Jakobshavn glacier in western Greenland. New research suggests the island's enormous ice sheet is more unstable than scientists previously believed.
 
If the ice sheet that blankets most of Greenland should melt, it would be catastrophic because sea levels would rise more than 20 feet. This would submerge coastal cities worldwide and threaten land that's home to at least 15 million Americans.
 
Scientists had believed that the world's second largest ice body had been relatively stable during the recent geological past. Even during periods of warming, the massive mantle of ice had remained largely intact, they thought.
 
But new research suggests that this assumption may be grossly off the mark.
 
JOE RAEDLE/GETTY IMAGES
 
A researcher observes a canyon created over time by a meltwater stream on the Greenland's ice sheet, July 16, 2013.
 
The Northern European country's ice sheet appears to have melted nearly completely at least once in the not-too-distant geological past, according to a groundbreaking study published on Thursday in the journal Nature.
 
By studying a sample of bedrock taken from beneath Greenland's ice deposit, researchers found that the autonomous Danish territory was ice-free (or "deglaciated") for "extended periods during the Pleistocene epoch," stretching from 2.6 million years to 11,700 years ago. Researchers estimate that the ice sheet shrunk to less than 10 percent of its current size and stayed that way for at least 280,000 years. 
 
Greenland's mighty ice sheet, it seems, may not be as impregnable as previously believed.
 
"Unfortunately, this makes the Greenland ice sheet look highly unstable," said study co-author Joerg Schaefer, a paleoclimatologist at Columbia University's Lamont-Doherty Earth Observatory, in a news release.
 
M. SANTINI/GETTY IMAGES
 
Icebergs that have broken off the Sermeq Kujalleq ice sheet, Qaasuitsup, Greenland.
 
Interestingly, another study published this week in the same edition of Nature revealed a significantly different picture of the ice sheet's past. Also a result of bedrock testing but from a sample taken from a different location, the paper concluded that Greenland had maintained at least some ice cover for the past 7.5 million years.  
 
Scientists say, however, that the two studies aren't necessarily contradictory ? and may in fact inform the other. Nearly all of Greenland's ice could've melted at certain times in the past, but some ice might've remained in areas of higher elevation. 
 
"Both studies show that there's the potential for the ice sheet to be quite dynamic and change over time," University of Vermont professor Paul Bierman, lead author of the second study, told Time magazine.
 
JOE RAEDLE/GETTY IMAGES
 
Water is seen on part of Greenland's glacial ice sheet, July 2013.
 
Authors of both papers agree that more research needs to be done to better understand the ice sheet's history. And global warming should be taken as a real and present threat to the future of the ice body ? and the planet as a whole. 
 
"We do what we're doing with the atmosphere right now at our own risk," Bierman told Time. "We're dealing with an incredibly complex system on Earth and we don't know the half of it. There are surprises lurking out there." 
 
Schaefer had a more direct warning. "We have to be prepared that this ice sheet might go again, and it might go again soon," he said, according to MIT Technology Review. 
 
"Soon," of course, is relative to geological time. It could take centuries or even millennia for all that ice to melt.
 
But there's still plenty of reason to be concerned. Greenland currently contributes about a quarter of the three millimeters that global sea levels rise every year ? and climate change could greatly accelerate the speed of the ice sheet's melting. "Projections of sea-level rise during this century hover around 3 or 4 feet, but many, including the one from the Intergovernmental Panel on Climate Change, do not take Greenland into account," states a blog post on Columbia's website. 
 
The impacts of climate change on Greenland are already being seen. 
 
The island's ice mantle is melting five times faster than it was in the 1990s, according to a 2012 study.
 
A Google Earth timelapse of northeast Greenland between 1984 and 2016 shows just how dramatic the melt has been on some parts of the country (use the scrollbar to move backwards and forwards in time):
 
 

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#18 grog

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Posted 19 September 2017 - 01:07 PM

Earth's Magnetic Field Flip Could Happen Sooner Than Expected
 
 
 
 
9 July 2014.
 
 
 
  
 
Changes measured by the Swarm satellite show that our magnetic field is weakening 10 times faster than originally predicted, especially over the Western Hemisphere
 
Changes measured by the Swarm satellite over the past 6 months shows that Earth's magnetic field is changing.
 
Shades of red show areas where it is strengthening, and shades of blue show areas that are weakening. Credit: ESA/DTU
 
Earth's magnetic field, which protects the planet from huge blasts of deadly solar radiation, has been weakening over the past six months, according to data collected by a European Space Agency (ESA) satellite array called Swarm.
 
The biggest weak spots in the magnetic field - which extends 370,000 miles (600,000 kilometers) above the planet's surface - have sprung up over the Western Hemisphere, while the field has strengthened over areas like the southern Indian Ocean, according to the magnetometers onboard the Swarm satellites - three separate satellites floating in tandem.
 
The scientists who conducted the study are still unsure why the magnetic field is weakening, but one likely reason is that Earth's magnetic poles are getting ready to flip, said Rune Floberghagen, the ESA's Swarm mission manager. In fact, the data suggest magnetic north is moving toward Siberia.
 
"Such a flip is not instantaneous, but would take many hundred if not a few thousand years," Floberghagen told Live Science. "They have happened many times in the past."[50 Amazing Facts About Planet Earth]
 
Scientists already know that magnetic north shifts. Once every few hundred thousand years the magnetic poles flip so that a compass would point south instead of north. While changes in magnetic field strength are part of this normal flipping cycle, data from Swarm have shown the field is starting to weaken faster than in the past. Previously, researchers estimated the field was weakening about 5 percent per century, but the new data revealed the field is actually weakening at 5 percent per decade, or 10 times faster than thought. As such, rather than the full flip occurring in about 2,000 years, as was predicted, the new data suggest it could happen sooner.
 
Floberghagen hopes that more data from Swarm will shed light on why the field is weakening faster now.
 
Still, there is no evidence that a weakened magnetic field would result in a doomsday for Earth. During past polarity flips there were no mass extinctions or evidence of radiation damage. Researchers think power grids and communication systems would be most at risk.
 
Earth's magnetic field acts like a giant invisible bubble that shields the planet from the dangerous cosmic radiation spewing from the sun in the form of solar winds. The field exists because Earth has a giant ball of iron at its core surrounded by an outer layer of molten metal. Changes in the core's temperature and Earth's rotation boil and swirl the liquid metal around in the outer core, creating magnetic field lines.
 
The movement of the molten metal is why some areas of the magnetic field strengthen while others weaken, Florberghagen said. When the boiling in one area of the outer core slows down, fewer currents of charged particles are released, and the magnetic field over the surface weakens.
 
"The flow of the liquid outer core almost pulls the magnetic field around with it," Floberghagen said. "So, a field weakening over the American continent would mean that the flow in the outer core below America is slowing down."
 
The Swarm satellites not only pick up signals coming from the Earth's magnetic field, but also from its core, mantle, crust and oceans. Scientists at the ESA hope to use the data to make navigation systems that rely on the magnetic field, such as aircraft instruments, more accurate, improve earthquake predictions and pinpoint areas below the planet's surface that are rich in natural resources. Scientists think fluctuations in the magnetic field could help identify where continental plates are shifting and help predict earthquakes.
 
These first results from Swarm were presented at the Third Swarm Science Meeting in Denmark on June 19.
 
 

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#19 grog

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Posted 19 September 2017 - 01:10 PM

Earth Timeline Snowball Earth
 
 
 
 
30 November 2016.
 
 
 
 
Artwork showing Snowball Earth
 
Snowball Earth describes a theory that for millions of years the Earth was almost entirely or wholly covered in ice, stretching from the poles to the tropics.
 
This freezing happened over 650 million years ago in the Pre-Cambrian, though it's now thought that there may have been more than one of these global glaciations. 
 
They varied in duration and extent but during a full-on snowball event, life could only cling on in ice-free refuges, or where sunlight managed to penetrate through the ice to allow photosynthesis.
 
Scientists always agreed on one ice age truth, the tropics cannot freeze... or can they?
 
Massive ice sheet melt created violent climate change and unleashed Earth's elemental powers.
 
Volcanoes defeat Snowball Earth
 
Volcanoes may have saved an ice-bound Earth.
 
The Snowball Earth hypothesis proposes that Earth's surface became entirely or nearly entirely frozen at least once, sometime earlier than 650 Mya (million years ago). Proponents of the hypothesis argue that it best explains sedimentary deposits generally regarded as of glacial origin at tropical paleolatitudes, and other otherwise enigmatic features in the geological record. Opponents of the hypothesis contest the implications of the geological evidence for global glaciation, the geophysical feasibility of an ice- or slush-covered ocean, and the difficulty of escaping an all-frozen condition. A number of unanswered questions exist, including whether Earth was a full snowball, or a "slushball" with a thin equatorial band of open (or seasonally open) water.
 
The snowball Earth episodes occurred before the sudden radiation of multicellular bioforms, known as the Cambrian explosion. The most recent snowball episode may have triggered the evolution of multicellularity. Another, much earlier and longer snowball episode, the Huronian glaciation, which occurred 2400 to 2100 Mya, may have been triggered by the first appearance of oxygen in the atmosphere, the "Great Oxygenation Event."
 
 

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#20 grog

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Posted 19 September 2017 - 01:12 PM

Earth Facing 'Mini Ice Age' In 15 Years As Sun Found To Be Cooling
 
 
 
22 October 2016.
 
 
 
 
So much for global warming - the earth is heading towards a mini ice age within 15 years, according to experts at Northumberland University.
 
So much for global warming - the earth is heading towards a mini ice age, according to experts at Northumberland University, with solar magnetic activity set to drop by up to 60 per cent in the next 15 years.
 
Research scientists say solar activity is currently at its lowest level for 300 years.
 
The last time it was this low London's Thames River froze over during a mini Ice Age that is now known as the Maunder Minimum.
 
A breakthrough model is allowing scientists to predict solar activity with more accuracy than ever before, and top scientists are now claiming that solar magnetic activity will more than halve between 2030 and 2040.
 
The Express reports:
 
The model looks at the Sun's '11-year heartbeat' - the period it takes for magnetic activity to fluctuate. This cycle was first discovered some 173 years ago.
 
However, a mathematician has established a more up-to-date model that can forecast what the solar cycles will look like based upon dynamo effects in two layers of the Sun.
 
Dynamo effects are a geophysical theory that dictate how the movement of the Earth's outer core conducts materials like liquid iron across the magnetic field to create an electric current - this also influences fluid motion beneath Earth's surface to create two magnetic fields along the axis of the Earth's rotation.
 
Worldwide temperatures are set to drop.
 
Professor Valentina Zharkova from Northumbria University applied this theory to the Sun, and was able to predict the affects of solar cycles with 97 per cent accuracy.
 
Ms Zharkova said at the National Astronomy Meeting: "We found magnetic wave components appearing in pairs, originating in two different layers in the Sun's interior.
 
"They both have a frequency of approximately 11 years, although this frequency is slightly different, and they are offset in time.
 
"Combining both waves together and comparing to real data for the current solar cycle, we found that our predictions showed an accuracy of 97 per cent."
 
Ms Zharkova says the next cycle is set to peak in 2022, and the cycle after, known as Cycle 26, will herald a new ice age.
 
She continued: "In Cycle 26, the two waves exactly mirror each other - peaking at the same time but in opposite hemispheres of the Sun.
 
"Their interaction will be disruptive, or they will nearly cancel each other. We predict that this will lead to the properties of a 'Maunder minimum'."
 
 

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