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Hubble sees cloudy 'super-Earth' 40 light-years away
This is an illustration of the hypothetical appearance of the exoplanet GJ 1214b, located 40 light-years from Earth. Spectroscopic observations with NASA's Hubble Space Telescope provide evidence of high clouds blanketing the planet. (Credit: NASA, ESA, and G. Bacon (STScI))
Two teams of scientists using NASA's Hubble Space Telescope report they have characterized the atmospheres of a pair of planets with masses intermediate between gas giants, like Jupiter, and smaller, rockier planets, like Earth.
A survey by NASA's Kepler space telescope mission previously showed that objects in this size range are among the most common type of planets in our Milky Way galaxy. The researchers described their work as an important milestone on the road to characterizing potentially habitable, Earth-like worlds beyond the solar system.
The two planets studied are known as GJ 436b and GJ 1214b. GJ 436b is categorized as a "warm Neptune" because it is much closer to its star than frigid Neptune is to our Sun. The planet is located 36 light-years away in the constellation Leo.
GJ 1214b is known as a "super-Earth" type planet. Super-Earths are planets with masses between that of Earth and Neptune. Because no such planet exists in our solar system, the physical nature of super-Earths is largely unknown. GJ1214b is located just 40 light-years from Earth, in the constellation Ophiuchus.
Both GJ 436b and GJ 1214b can be observed passing in front of, or transiting, their parent stars. This provides an opportunity to study these planets in more detail as starlight filters through their atmospheres.
An atmospheric study of GJ 436b based on such transit observations with Hubble over the last year is presented in one of the papers, led by Heather Knutson of the California Institute of Technology in Pasadena, Calif. The news is about what they didn't find. The Hubble spectra were featureless and revealed no chemical fingerprints whatsoever in the planet's atmosphere.
"Either this planet has a high cloud layer obscuring the view, or it has a cloud-free atmosphere that is deficient in hydrogen, which would make it very unlike Neptune," said Knutson. "Instead of hydrogen, it could have relatively large amounts of heavier molecules such as water vapor, carbon monoxide, and carbon dioxide, which would compress the atmosphere and make it hard for us to detect any chemical signatures."
Evidence of high clouds
Observations similar to those obtained for GJ 436b had been previously obtained for GJ 1214b. The first spectra of this planet were also featureless and presented a similar puzzle: The planet's atmosphere either was predominantly water vapor or hydrogen-dominated with high-altitude clouds.
A team of astronomers led by Laura Kreidberg and Jacob Bean of the University of Chicago used Hubble to obtain a deeper view of GJ 1214b that revealed what they consider definitive evidence of high clouds blanketing the planet. These clouds hide any information about the composition and behavior of the lower atmosphere and surface. The new Hubble spectra also revealed no chemical fingerprints whatsoever in the planet's atmosphere, but the high precision of the new data enabled them to rule out cloud-free compositions of water vapor, methane, nitrogen, carbon monoxide, or carbon dioxide for the first time.
"Both planets are telling us something about the diversity of planet types that occur outside of our own solar system; in this case we are discovering that we may not know them as well as we thought," said Knutson. "We'd really like to determine the size at which these planets transition from looking like mini-gas giants to something more like a water world or a rocky, scaled-up version of the Earth. Both of these observations are fundamentally trying to answer that question."
Models of GJ 436b and GJ 1214b predict clouds that could be made out of potassium chloride or zinc sulfide at the scorching temperatures of several hundred degrees Fahrenheit predicted to be found in these atmospheres. "You would expect very different kinds of clouds to form on these planets than you would find, say, on Earth," said Kreidberg.
The Chicago team had to make a big effort to conclusively determine the nature of GJ 1214b's cloudy atmosphere. Kreidberg explained, "We really pushed the limits of what is possible with Hubble to make this measurement  -  our work devoted more Hubble time to a single exoplanet than ever before. This advance lays the foundation for characterizing other Earths with similar techniques.
"Looking forward, the James Webb Space Telescope will be transformative. The new capabilities of this telescope will allow us to peer through the clouds on GJ 1214b and similar exoplanets."
Abstract of Nature paper (Laura Kreidberg et al.)
Recent surveys have revealed that planets intermediate in size between Earth and Neptune ('super-Earths') are among the most common planets in the Galaxy. Atmospheric studies are the next step towards developing a comprehensive understanding of this new class of object. Much effort has been focused on using transmission spectroscopy to characterize the atmosphere of the super-Earth archetype GJ 1214b, but previous observations did not have sufficient precision to distinguish between two interpretations for the atmosphere. The planet's atmosphere could be dominated by relatively heavy molecules, such as water (for example, a 100 per cent water vapour composition), or it could contain high-altitude clouds that obscure its lower layers. Here we report a measurement of the transmission spectrum of GJ 1214b at near-infrared wavelengths that definitively resolves this ambiguity. The data, obtained with the Hubble Space Telescope, are sufficiently precise to detect absorption features from a high mean-molecular-mass atmosphere. The observed spectrum, however, is featureless. We rule out cloud-free atmospheric models with compositions dominated by water, methane, carbon monoxide, nitrogen or carbon dioxide at greater than 5σ confidence. The planet's atmosphere must contain clouds to be consistent with the data.
Abstract of Nature paper (Heather A. Knutson et al.)
GJ 436b is a warm  -  approximately 800 kelvin  -  exoplanet that periodically eclipses its low-mass (half the mass of the Sun) host star, and is one of the few Neptune-mass planets that is amenable to detailed characterization. Previous observations have indicated that its atmosphere has a ratio of methane to carbon monoxide that is 105 times smaller than predicted by models for hydrogen-dominated atmospheres at these temperatures. A recent study proposed that this unusual chemistry could be explained if the planet's atmosphere is significantly enhanced in elements heavier than hydrogen and helium. Here we report observations of GJ 436b's atmosphere obtained during transit. The data indicate that the planet's transmission spectrum is featureless, ruling out cloud-free, hydrogen-dominated atmosphere models with an extremely high significance of 48σ. The measured spectrum is consistent with either a layer of high cloud located at a pressure level of approximately one millibar or with a relatively hydrogen-poor (three per cent hydrogen and helium mass fraction) atmospheric composition.
Laura Kreidberg et al., Clouds in the atmosphere of the super-Earth exoplanet GJ 1214b, Nature, 2014, DOI: 10.1038/nature12888 Heather A. Knutson et al., A featureless transmission spectrum for the Neptune-mass exoplanet GJ 436b, Nature, 2014, DOI: 10.1038/nature12887 Related:
Hubble Sees Cloudy Super-Worlds with Chance for More Clouds Topics: Physics/Cosmology share | e-mail
January 5, 2014 by Gorden Russell Okay, melajara, I Googled and found out that we have a radio "bubble" of 110 light years traveling outwards But when I searched to see how many habitable stars were at that distance, all I found was a star map of stars like ours at a range of 50 light years.

"This is a map of every star within 50 light years visible with the naked eye from Earth. There are 133 stars marked on this map. Most of these stars are very similar to the Sun and it is probable that there are many Earth-like planets around these stars. There are roughly 1400 star systems within this volume of space containing 2000 stars, so this map only shows the brightest 10% of all the star systems, but most of the fainter stars are red dwarfs. "
I don't have much hope for red dwarfs, so don't bother looking at them for the short term. A cobbler should stick to his last, and spectral class G is what we've grown up with.
There is quite a list of stars to look at. It starts with the Alpha Centauri system, which I've been studying since childhood. We know of no livable world there yet, but a lot of astronomers are still looking, so keep up your hopes but don't hold your breath.
Saturday Night Live is coming on now, so I'll look into the other stars later.
Log in to Reply January 4, 2014 by Gorden Russell Here, melajara, from the Wikipedia page for "Astrobiology."
Rare Earth hypothesis[edit]
Main article: Rare Earth hypothesis
This hypothesis states that based on astrobiological findings, multi-cellular life forms found on Earth may actually be more of a rarity than scientists initially assumed. It provides a possible answer to the Fermi paradox which suggests, "If extraterrestrial aliens are common, why aren't they obvious?" It is apparently in opposition to the principle of mediocrity, assumed by famed astronomers Frank Drake, Carl Sagan, and others. The Principle of Mediocrity suggests that life on Earth is not exceptional, but rather that life is more than likely to be found on innumerable other worlds.
The anthropic principle states that fundamental laws of the universe work specifically in a way that life would be possible. The anthropic principle supports the Rare Earth Hypothesis by arguing the overall elements that are needed to support life on Earth are so fine-tuned that it is nearly impossible for another just like it to exist by random chance (note that these terms are used by scientists in a different way from the vernacular conception of them). However, Stephen Jay Gould compared the claim that the universe is fine-tuned for the benefit of our kind of life to saying that sausages were made long and narrow so that they could fit into modern hot dog buns, or saying that ships had been invented to house barnacles.[109][110]
Now I would disagree with Gould, in that, if you have the proper temperature, pressure, and available chemical compounds, the biochemistry of life just kind of falls together, in "self-assembly" (like I am always talking about).
If everything is just so, a Goldilocks world that survives long enough will be bound to have life. But there are so many things that need to be "just so," that living worlds may be few and fare apart...and intelligent life may not be a sure thing.
But with all those billions of stars of spectral class G out there, there are bound to be thousands of worlds with marvelous life forms, just waiting for us to go and gaze upon them. But there might not be many life forms that we can talk to.
Log in to Reply January 4, 2014 by Gorden Russell Oh, it turns out that Tennyson wrote:
"Who trusted God was love indeed
And love Creation's final law
Tho' Nature, red in tooth and claw
With ravine, shriek'd against his creed"
Log in to Reply January 3, 2014 by Trance_Ender Hey Gorden - Remember John Varley's "The Ophiuchi Hotline"?
Log in to Reply January 3, 2014 by Gorden Russell I remember reading the reviews to that book, and was a big fan of Varley and wanted that book so bad...but I was living in Redrum County, OH back then and there was only one small library with a limited selection. Now that I'm back in NY, I'll be able to find a copy.
Log in to Reply January 2, 2014 by Gorden Russell To see what the Hubble is still capable of makes me very eager to what the Webb will discover.
Log in to Reply January 3, 2014 by Trance_Ender Colonization opportunities everywhere you look up in the night sky ...
Log in to Reply January 3, 2014 by Peter the printer Colonisation? How exactly?
Log in to Reply January 3, 2014 by Trance_Ender Colonist families arriving on starships traveling at near-relativistic speeds.
Log in to Reply January 4, 2014 by smb12321 Yeah, except for little problems like the means to preserve and maintain life on such a vessel, the efficacy of such a world and, oh yeah, a starship with near-relativistic speeds. Besides these doodads we're ready to fly.
Log in to Reply January 4, 2014 by Gorden Russell These ships will be immense, dozens of miles across and hundreds of miles long. Plenty to room to store or grow food. Just growing sugarcane will give you the glucose for culturing meat cells.
When there are billions of robots mining the near Earth asteroids, the ships will be built in a few years.
Now when a robot can replicate itself in one day, then after 30 days of doubling their numbers every day, there will be over a billion robots.
Log in to Reply January 4, 2014 by Gorden Russell Oh yeah, I forgot to mention, every time a robot prints out a copy of itself, it has to print out a copy of the 3-D printer it used, and a copy of the solar array it used to power everything.
But after that, all those robots and printers can print up a lot of bits and pieces for insystem robotic mining ships.
After those are working in the tens of thousands, then they will have what they need to build starships.
Log in to Reply January 4, 2014 by melajara When I'm reading this, the Fermi's paradox haunts me even more, but "where are they?"
Log in to Reply January 4, 2014 by Gorden Russell Carl Sagan had a lot to say about this, Melajara. He talked a lot about the apparent absence of aliens on his greatly renowned PBS series, "Cosmos."
But maybe you're too young to remember it. Years ago, all the big county libraries had this on VHS. I don't know if it has been released on DVD.
One thing he mentioned is that civilizations are warlike and could destroy themselves before they become star travelers.
My first major in college, back at SUNY Ag & Tech at Morrisville, was Med Lab Tech. I had to change majors 'cuz I could not pay attention in General Chemistry. But I aced all of my Biology courses, including two semesters of Zoology. So I can tell you, all of nature is in competition with every other living thing (except for the few that are in symbiotic relationships  -  but even those are in a "you and me against the world" kind of partnership (like those stinging ants of Australia that protect the thorn bush that has evolved passageways and openings to aid the ants in their daily business)). Was it Blake who wrote the poem with the line, "Nature red in tooth and claw?" Well, all he said was true.
So any aliens evolving on any other world will be competitive and may have destroyed their world with nuclear war (or global warming) before they ever took to travel between the stars.
Another thing is that the galaxy is vast and old. Other races could be too far away for us to have met them. Or maybe we are the most advanced in the neighborhood and the others haven't discovered radio waves yet. The gas and dust between the stars absorbs radio waves and after a certain distance, we can only pick up radio waves from all the natural sources that would block out the signals of other peoples. Or they could be communicating with modulated lasers or entangled particle telegraphs.
Or...the other races are all so advanced that they are living in a Sing of their own that gives them all abundant lives. So maybe that means that they aren't so competitive any more, and they have become wise and beneficent. Maybe they are watching us right now, and are waiting for us to get past the Sing and into the coming era of the abundant life where normal people won't need to struggle against each other to meet their daily needs.
Now maybe you have seen my other comments, where I say that after we have the self-assembling photo-voltaic carbon nanocells that take carbon out of the air and use it to build everything we need out of nanotubes and graphene and every other useful carbon compound (they'll even be able to mine the old landfills and break down all of the harmful chemical compounds that are leaching into water tables, and bring up all the discarded heavy metals and put them into new electronics (like robots)).
Maybe these old and wise peoples are just waiting for us to discover warp drive so that they can welcome us into the Federation of Planets.
But there is also the problem of "Rare Earths."
Yes, there are billions of stars like Sol out there, but it takes a lot of things to make an Earth-like habitable world.
Just look at nearby Venus.
Venus is only a little bit smaller than Earth, and has been called a sister planet. Yet she has air pressure of CO2 that equals the pressure of our sea, many miles down. Her air temperature is hotter than your kitchen oven can reach.
If you are curious, and have the time, there is a good Wikipedia entry:

There is also, I think, a wiki on the "Rare Earth" problem. Let me go look for it.
Log in to Reply January 4, 2014 by Gorden Russell Look at this, Carl Sagan's "Cosmos" is on YouTube:

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