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exoplanets life

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#21 grog

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Posted 19 September 2017 - 01:24 PM

Earth Faces Sixth Mass Extinction Event
 
 
 
 
09 December 2016.
 
 
 
 
Scientists warn that Earth faces its sixth mass extinction event soon
 
An astonishing new study suggests that Earth is will face its sixth mass extinction of all animal life on the planet, including humans, within 50 years time. 
 
According to one of the world's top biologists, Professor John Wiens, almost half of the world's species are suffering local extinctions due to climate change.
 
Independent.co.uk reports:
 
Professor Wiens, who is editor of the Quarterly Review of Biology and a winner of the American Society of Naturalists' Presidential Award, said the implications for the future were serious because his review showed plants and animals were struggling to deal with the relatively small amount of global warming experienced to date.
 
So far the world has warmed by about 1C above pre-industrial levels, but it is expected to hit between 2.6 and 4.8C by 2100 if nothing is done to reduce greenhouse gases.
 
Another problem facing life on Earth is the election of climate science denier Donald Trump as US president.
 
Professor Wiens, of Arizona University, described this as a "global disaster" and, when asked what he would say to the President-elect if he met him, he joked grimly: "Kill yourself immediately."
 
In his study, published in the journal PLOS Biology, the scientist examined academic papers about 976 different species from all over the world that had been studied at least twice, once about 50 years ago and again within the last 10 years.
 
"In almost half the species looked at, there have been local extinctions already," he said.
 
"This is stuff that's already happened with just a small change to the climate. We're looking at a two to five-fold increase [in warming over the next century].
 
"What it shows is species cannot change fast enough to keep up with a small change in climate. That's the big implication - even a small change in temperature and they cannot handle it."
 
The study looked at 716 different kinds of animals and 260 plants from Asia, Europe, North and South America, and elsewhere.
 
Local extinctions were found to have occurred among 47.1 per cent of species at the "warm edge" of their traditional range, as it became too hot for them. There were few areas of the planet that were unaffected.
 
"Overall, the frequency of local extinctions was similar across most climatic zones, habitats, gradients and clade," the PLOS Biology paper said.
 
However Professor Wiens found climate-related local extinctions were "substantially higher" among freshwater species at 74 per cent of the 31 studied.
 
The current rate of global extinction of animals and plants is believed to be faster than some of the five great extinction events in the Earth's history, but so far the total number lost does not compare to the species lost when the dinosaurs were wiped out about 65 million years ago.
 
However one reason geologists are considering declaring a new epoch in the planet's history is the rapid loss of flora and fauna that will have a noticeable effect on the fossil record.
 
Professor Wiens said: "It's true that in terms of global extinction of entire species that have already happened, I think we're not there [at the sixth mass extinction] yet.
 
"But I think unfortunately we are on track for that to happen.
 
"That's sort of the good news - it hasn't happened yet. But if we don't do anything it seems like that's going to happen in the next 50 to 100 years."
 
There were already "two bad signs" that Mr Trump's election would make things worse, Professor Wiens said.
 
"One would be this person he's assigned to head the EPA [renowned climate science denier Scott Pruitt] and the other thing is pulling out of the Paris accord [on climate change]," he said.
 
"The EPA in this country, they are the ones supposed to be protecting the environment."
 
In what was perhaps a sign of the desperation felt by environmental scientists in the US and elsewhere, he jokingly suggested the UK should invade the US or the US and Canada should swap leaders with Justin Trudeau taking over in the White House.
 
Asked what he would really say to Mr Trump if they met, Professor Wiens said: "I guess I would tell him 'what would you think if there was a country on the other side of the world that was releasing gas that was going to cause extinctions in our country, to hurt our crops and make people starve'.
 
"He would say, 'tell me where it is and we'll bomb them tomorrow'. Then I'd say, 'this is what we're doing to other countries because we are the big polluters.'
 
"People are already having serious problems with food security. People are going to die and it's going to be the fault of our country and other big polluters.
 
"There is no question he would militarily intervene against a country that was doing to us what we are doing to other countries."
 
 

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#22 grog

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Posted 19 September 2017 - 01:27 PM

AN EARTH-LIKE PLANET ONLY 16 LIGHT YEARS AWAY?
 
 
 
20 April 2016
 
 
 
 
Earth may have a new neighbour, in the form of an Earth-like planet in a solar system only 16 light years away. The planet orbits a star named Gliese 832, and that solar system already hosts two other known exoplanets: Gliese 832B and Gliese 832C. The findings were reported in a new paper by Suman Satyal at the University of Texas, and colleagues J. Gri?th, and Z. E. Musielak.
 
Gliese 832B is a gas giant similar to Jupiter, at 0.64 the mass of Jupiter, and it orbits its star at 3.5 AU. G832B probably plays a role similar to Jupiter in our Solar System, by setting gravitational equilibrium. Gliese 832C is a Super-Earth about 5 times as massive as Earth, and it orbits the star at a very close 0.16 AU. G832C is a rocky planet on the inner edge of the habitable zone, but is likely too close to its star for habitability. Gliese 832, the star at the center of it all, is a red dwarf about half the size of our Sun, in both mass and radius.
 
The newly discovered planet is still hypothetical at this point, and the researchers put its mass at between 1 and 15 Earth masses, and its orbit at between 0.25 to 2.0 AU from Gliese 582, its host star.
 
The two previously discovered planets in Gliese 832 were discovered using the radial velocity technique. Radial velocity detects planets by looking for wobbles in the host star, as it responds to the gravitational tug exerted on it by planets in orbit. These wobbles are observable through the Doppler effect, as the light of the affected star is red-shifted and blue-shifted as it moves.
 
The team behind this study re-analyzed the data from the Gliese 832 system, based on the idea that the vast distance between the two already-detected planets would be home to another planet. According to other solar systems studied by Kepler, it would be highly unusual for such a gap to exist.
 
As they say in their paper, the main thrust of the study is to explore the gravitational effect that the large outer planet has on the smaller inner planet, and also on the hypothetical Super-Earth that may inhabit the system. The team conducted numerical simulations and created models constrained by what's known about the Gliese 832 system to conclude that an Earth-like planet may orbit Gliese 832.
 
This can all sound like some hocus-pocus in a way, as my non-science-minded friends like to point out. Just punch in some numbers until it shows an Earth-like planet, then publish and get attention. But it's not. This kind of modelling and simulation is very rigorous.
 
Putting in all the data that's known about the Gliese 832 system, including radial velocity data, orbital inclinations, and gravitational relationships between the planets and the star, and between the planets themselves, yields bands of probability where previously undetected planets might exist. This result tells planet hunters where to start looking for planets.
 
In the case of this paper, the result indicates that "there is a slim window of about 0.03 AU where an Earth-like planet could be stable as well as remain in the HZ." The authors are quick to point out that the existence of this planet is not proven, only possible.
 
The other planets were found using the radial velocity method, which is pretty reliable. But radial velocity only provides clues to the existence of planets, it doesn't prove that they're there. Yet. The authors acknowledge that a larger number of radial velocity observations are needed to confirm the existence of this new planet. Barring that, either the transit method employed by the Kepler spacecraft, or direct observation with powerful telescopes, may also provide positive proof.
 
So far, the Kepler spacecraft has confirmed the existence of 1,041 planets. But Kepler can't look everywhere for planets. Studies like these are crucial in giving Kepler starting points in its search for exoplanets. If an exoplanet can be confirmed in the Gliese 832 system, then it also confirms the accuracy of the simulation that the team behind this paper performed.
 
If confirmed, G832 C would join a growing list of exoplanets. It wasn't long ago that we knew almost nothing about other solar systems. We only had knowledge of our own. And even though it was always unlikely that our Solar System would for some reason be special, we had no certain knowledge of the population of exoplanets in other solar systems.
 
Studies like this one point to our growing understanding of the dynamics of other solar systems, and the population of exoplanets in the Milky Way, and most likely throughout the cosmos.

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#23 grog

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Posted 19 September 2017 - 01:33 PM

A Trillion Alien Civilizations?
 
 
 
 
 
 
 
Another example that had the internet buzzing for many weeks involved several articles and posts claiming that "at least a trillion alien civilizations have almost certainly existed in the universe."3 These claims are founded on four presuppositions:
 
1. The density and kinds of planets throughout our galaxy and all other galaxies in the universe are roughly the same as what we observe in the vicinity of our solar system.
 
2. About 20 percent of all planets are habitable.
 
3. Life inevitably will arise on all habitable planets.
 
4. The probability of a technologically advanced civilization arising from simple life forms is better than one chance in 10 billion.
 
Origins of Life (my book coauthored with biochemist Fazale Rana) demonstrates that, from a naturalistic perspective, assumption #3 is certainly incorrect. The probability of life originating naturalistically on a habitable planet is mathematically indistinguishable from zero.4 Since zero times any other factor or set of factors equals zero, then, from a naturalistic perspective, the number of civilizations besides our own that exist in the universe is zero.
 
The Trouble with the 20 Percent Assumption
 
There is also much I could say about why assumptions #1 and #4 are deeply flawed, but I will focus on #2 and a new discovery that establishes that far, far less than 20 percent of all planets are habitable.
 
Assumption #2 only takes into account the "water habitable zone," which is the range of distances from a planet's host star within which-and only within which-it would conceivably be possible for liquid water to exist at some place on the planet's surface at some time during the planet's history. And, indeed, about 20 percent of the more than 3,000 planets discovered so far fall within this water habitable zone.
 
The percentage drops precipitously, however, if one does not allow the greenhouse effect of the planet's atmosphere to take on a value that perfectly compensates for the host star's brightness. And the percentage takes another steep drop if one desires the planet to retain liquid water on more than 10 percent of its surface for more than a billion years. (Liquid water must be present on a planet's surface for at least 3.5 billion years for there to be even the remotest possibility of the planet sustaining advanced life.)
 
Eight Habitable Zones
 
Moreover, in addition to the water habitable zone, there are seven other known habitable zones. I listed and briefly described these zones in "Earth in the Zone," an article I wrote two years ago for Salvo 30 (Fall 2014). For those who missed the article or need a refresher, here again is a list of the eight zones:
 
1. Water habitable zone
 
2. Ultraviolet habitable zone
 
3. Photosynthetic habitable zone
 
4. Ozone habitable zone
 
5. Planetary rotation rate habitable zone
 
6. Planetary obliquity habitable zone
 
7. Tidal habitable zone
 
8. Astrosphere habitable zone
 
In chapter 7 of my just-released book, Improbable Planet, I provide a detailed, thoroughly documented explanation of all eight of these habitable zones.5
 
Typically, these zones do not overlap. For example, the distance a planet must be from its host star so that it receives enough ultraviolet radiation to enable the synthesis of many life-essential compounds, but not so much as to kill living things, is rarely the same distance that a planet must be from its host star for liquid water to possibly exist on its surface. For 97 percent of all stars, the liquid water habitable zone does not overlap the ultraviolet habitable zone.
 
A planet is a true candidate for habitability only if it simultaneously resides in all eight habitable zones. So far, the only known planet that dwells in all eight is Earth.
 
Venus's Desiccating Factor
 
Now, a ninth habitable zone has been discovered-
 
9. Electric wind habitable zone.6
 
This zone was discovered thanks to an electron spectrometer on board the European Space Agency's spacecraft Venus Express. This instrument measured the electric potential in Venus's atmosphere. The result was surprising. At 10 volts, Venus's atmospheric electric field proved to be far stronger than what any astronomer had expected.
 
The high voltage drives an electric wind in Venus's atmosphere that is powerful enough to drive all heavy ions (atomic nuclei stripped of their electrons) in Venus's ionosphere into interplanetary space. These heavy ions include oxygen ions that once belonged to water molecules.
 
Previously, astronomers had presumed that the solar wind was responsible for drying out Venus. This new discovery shows that Venus's electric field is the dominant desiccating factor.
 
But the Sun still plays a role, though less directly. The Venus Express research team determined that Venus's proximity to the Sun explains its strong atmospheric electric field. Venus receives twice as much ultraviolet radiation as does Earth. All this ultraviolet radiation results in a high density of free electrons and ions in Venus's atmosphere, which generates a strong electric field above the planet's surface.7
 
Confirmation that Venus's proximity to the Sun explains its strong atmospheric electric field comes from failed attempts to detect strong atmospheric electric fields either on Earth or on Mars. Instruments establish that both Earth and Mars possess atmospheric electric fields weaker than 2 volts.8
 
It's Distance, Not Atmosphere
 
The discovery of a strong atmospheric electric field on Venus has serious implications for the possible habitability of exoplanets (planets beyond our solar system). The discovery implies that any planet that has an atmosphere thicker than one percent of Earth's and that is closer to its star than about 90 percent of Earth's distance from the Sun will very likely possess an atmospheric electric field strong enough to completely dry out the planet.
 
It has been known for some time that planets with atmospheres thinner than one percent of Earth's will be unable to prevent deadly radiation, which emanates both from their host stars and from cosmic rays, from penetrating to their surfaces. These planets will also have a water problem. With such thin atmospheres, the boiling point of water will not be greater than the freezing point, implying that liquid water will be absent from their surfaces. For these two reasons, planets with atmospheres thinner than one percent of Earth's cannot be classified as habitable.
 
What the discovery of a strong electric field on Venus means, with respect to habitability, is that, for planets closer to their host stars than 90 percent of Earth's distance from the Sun, it does not matter how thick their atmospheres are. If the atmospheres are thinner than one percent of Earth's, they will dry out, because they will not be able to hold liquid water. But if the atmospheres are thicker than one percent of Earth's, they also will dry out, because the strong electric field in their atmospheres will desiccate them.
 
This set of conclusions has enormous implications. The vast majority (over 95 percent) of exoplanets currently classified as "habitable" are closer to their stars than 90 percent of Earth's distance from the Sun. Thus, they no longer can be classified as habitable. To put it another way, for the vast majority of stars, the water habitable zone does not overlap the electric wind habitable zone.
 
Nine Zones Required
 
The discovery of the electric wind habitable zone means that for a planet to be a viable candidate for possibly sustaining life, it must simultaneously reside in nine different habitable zones. So far, astronomers have measured the characteristics of 3,484 planets.9 Only one of all these 3,484 planets resides in all nine known habitable zones. That one is Earth.
 
Given the fine-tuning inherent in each of the nine known habitable zones, and given the extreme improbability that even three of them will overlap, let alone all nine, it seems that nothing less than the supernatural handiwork of a Creator will suffice to explain how a planet could meet all these known conditions for habitability. •

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#24 grog

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Posted 19 September 2017 - 01:40 PM

 
 
 
 
 
A metre of snow falls in the Sahara desert
 
 
 
January 22, 2017
 
 
 
The most snow to fall in living memory is currently coating the desert sands of the Sahara.
 
A month after the largest hot desert on the planet experienced the first snowfall in nearly 40 years, the white powder has returned, and in greater volume.
 
Residents of Aïn Séfra, Algeria, were greeted this morning by a metre of snow, twice as much as has fallen in most ski resorts in the French Alps over the last week.
 
The snow has caused chaos in the town known as the Gateway to the Desert, with buses stranded on icy roads, while children have taken advantage of the flurry, building snowman and sledging down dunes.
 
Before last December it was in 1979 that Aïn Séfra, where the Atlas Mountains meet the desert, last saw snow.
 
Though the town is in the Sahara, its average January temperature is about 6C degrees, while in July the mercury regularly reaches 38C degrees.
 
Temperatures elsewhere in "the Greatest Desert", which stretches across Algeria, Chad, Libya, Mali and Morocco, have previously passed 47C degrees.

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