Nasa / Space

Geek Trivia: Home away from home(world)

Which of the several hundred known and suspected planets outside our local solar system has enough characteristics in common with Earth that scientists believe it has a reasonable chance of supporting a recognizable form of life?
Which of the several hundred known and suspected planets outside our local solar system has enough characteristics in common with Earth that scientists believe it has a reasonable chance of supporting a recognizable form of life?

The planet in question is Gliese 581 c, which orbits the red dwarf star Gliese in the constellation Libra, about 20 light years away from Earth. While Gliese 581 c is about five times the mass of Earth -- one of our aforementioned Super-Earths -- it has an estimated mean surface temperature of about 290 Kelvin, which is just barely hotter than the mean temperature on Earth . The reason for Gliese 581 c's relatively temperate surface conditions is owed mostly to the planet's orbit -- it sits in (or at least near) the so-called Goldilocks Zone, an orbital distance from its parent star that gives it an hospitable, regular surface temperature very similar to Earth.

The known habitable temperature range of all life on Earth -- the only ecosphere of which we have direct knowledge -- is between 258 and 394 Kelvin, which is devastatingly narrow by planetary standards. That slim range also includes the most radical thermal extremophiles known to science: Antarctic cryptoendoliths and thermophilic bacteria found in deep sea volcanic vents. So far, Gliese 581 c is the only exoplanet thought to maintain a mean surface temperature within this range.

As to whether Gliese 581 c has the other unconditional requirement for known forms of life -- water -- the jury is still out. Scientists have an estimated mass for Gliese 581 c, but not an estimated density. So those five Earth masses could be a life silicate or iron rock, a hydrogen/helium "gas dwarf," a carbon-crystal "diamond planet," an exotic super-hot world made of Ice VII, or -- most hopefully -- a water-ice world with a rocky core and a surface gravity about 1.25 times that of Earth.

As of right now, only one extrasolar planet has a confirmed presence of water vapor in its atmosphere -- planet HD 189733 b -- and it shouldn't. HD 189773 b has both water vapor and methane in its atmosphere, and the two should react to create carbon monoxide, but for some reason don't. And even if scientists could figure out what keeps the water vapor around, HD 189773 b's mean surface temperature of 1138 Kelvin makes it a pretty inhospitable vacation spot, anyway.

Thus, Gliese 581 c remains our most compelling Class M planet candidate, though one still shrouded in uncertainty. That's not just some extraordinary extrasolar exceptionalism; it's a statistically significant slice of star-spanning Geek Trivia.

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Jay Garmon has a vast and terrifying knowledge of all things obscure, obtuse, and irrelevant. One day, he hopes to write science fiction, but for now he'll settle for something stranger -- amusing and abusing IT pros. Read his full profile. You can a...

13 comments
Brother Martin de Porres
Brother Martin de Porres

It's Koine Greek for Geodesic, as in Apocalypse of St John. That great big Gas Giant Diamond Core. 1500 miles diameter, with 12 hub points, like all respectable geodesic icosahedral spheres. Mind the pearly gates folks, they are spherical air-locks. The twelve foundations are concentric (onion) layers. One day our own Gas Giants will be Sculpted into Inter-Stella Voyagers. Father Jose Director of The Vatican Observatory, can fill you in on exra-terrestrial archive material. It's not them, who are out of communion,...it's us! All will shortly be revealed. Check out Revelations Ch 21 & 22. 22:8 Now I, John, am the one who heard and saw these things. When I heard and saw, I fell down to worship before the feet of the angel who had shown me these things. 22:9 He said to me, "See you don't do it! ;) I am a fellow bondservant with you and with your brothers, :) the prophets, and with those who keep the words of this book. Worship God." 22:10 He said to me, "Don't seal up the words of the prophecy of this book, for the time is at hand. It's OK... ANGELS ARE VERY FRIENDLY!...AND INCREDIBLY GOOD LOOKING! Happy Thanksgiving from H.H. Pope Benedict XVI,

Poodoo999
Poodoo999

"ANGELS ARE VERY FRIENDLY!...AND INCREDIBLY GOOD LOOKING!" Yes, but are they anatomically correct?

Roscojim
Roscojim

Umm...huh? Like Fozzie said in "The Muppet Movie", "Looks like we picked up a weirdo..." :-)

catpro-54
catpro-54

when I read his response......

Poodoo999
Poodoo999

Heck, if we're going to quibble about spelling, let's go for the grammar, too! The first paragraph has the phrase "us mere humans" which I believe should be "we mere humans" instead. If you take out the modifier (mere humans), the sentence should still make sense. Would you say "we use" or "us use"? I know nothing about astrology (see? told 'ya!) so I can't quibble about the rest of it.

Popoyd
Popoyd

Astronomy, not astrology =P which actually reinforces your point there. The first is a science, the second is... arguable at best. Sorry, couldn't help it =)

Deadly Ernest
Deadly Ernest

When I went to school I was taught you used the word 'a' before words unless they started with a vowel and then you used the word 'an' - so you buy a drill bit and an auger. I spotted in the first paragraph of page 2 today you wrote "...gives it an hospitable..." - at first I thought this may be a new teaching thing and asked my sister who teachers high school English - nope no change she knows of. So I now wonder if this is another of those regional things like how you people from the Americas can't spell words like colour or honour properly.

K Winn
K Winn

The article depends on the pronunciation, not the spelling, so it's "an hour," "a hospital," "an honor," etc. Words like "historic" where some people pronounce the "h" and others don't are up for grabs. Now for another word choice issue. "Everyday" means commonplace, not daily or regularly. If you intend one of those, then the phrase is "every day." Just remember the Glen Campbell song "(Such are) the dreams of the everyday housewife," and you'll know that "everyday" means something other than "daily."

swstephe
swstephe

Actually, it is "an" before anything that sounds like it starts with a vowel. Many words borrowed from French have "silent H", so they sound like they start with vowels and using "an" is appropriate. You would write "an hour" and "an honor", not "a hour" and "a honor", right? Hospitable is from French, so it is potentially valid, depending on how you pronounce it.

Nicholas.Newman@Skynet.be
Nicholas.Newman@Skynet.be

Yes but not all "h"s from French words are silent - some are "aspir?s". For example in "un handicap" one does not pronounce the "n" because the "h" of "handicap" is pronounced, although slightly. Hence "a handicap" rather than "an handicap". There are many other examples, one being "h?pital" with a silent "h" but "a hospital" because we choose to pronounce the "h". Also gender can come into it as "une" has its "n" pronounced in all cases. Further, many words which could be deemed to come from the French actually come from Latin in both French and English.

Deadly Ernest
Deadly Ernest

"'E's at an 'ospital." or "An 'orror." Yeah, I can see some sense in an hour based on the sound, although I was taught a hour. BTW: horror is is usually pronounced, in most English dialects with a 'h' sound like in 'huh' as 'h-orror' with an audible h; very similar to horse and house and how.

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