By now you’ve probably seen headlines such as A Habitable Exoplanet — for Real This Time. Phil Plait has a more sober assessment. Still, he concludes:
But perhaps the most interesting and exciting aspect of all this is what it implies. The Milky Way galaxy is composed of about 200 billion stars, and is 100,000 light years across. The fact that we found a planet that is even anything like the Earth at all orbiting another star only 20 light years away makes me extremely optimistic that earthlike planets are everywhere in our galaxy. 20 light years is practically in our lap compared to the vast size of our galaxy, so statistically speaking, it seems very likely it’s not unique. I don’t want to extrapolate from a data set of two (us and them), but if this is typical, there could be millions of such planets in the galaxy. Millions.
So we don’t know if this planet is all that much like Earth — the surface gravity may be quite high if it’s dense and small, for example, or it may not have any air, or it may have a thick atmosphere like Venus — but what it’s telling us is that smaller, lower mass planets at the right distance from their star for liquid water are almost certainly common in the galaxy.
I assume this means we can play around with the Drake equation? In any case, I am now reminded of Poul Anderson’s essay “The creation of imaginary worlds: the world builder’s handbook and pocket companion.” You can read most of the essay online at Google Books. Or, find it in Writing Science Fiction & Fantasy. For us “squishy science” lovers the biochemist Hal Clament has an essay which follow’s Anderson’s which outlines how to create imaginary life.
Razib Khan’s degrees are in biochemistry and biology. He has blogged about genetics since 2002, previously worked in software development, is an Unz Foundation Junior Fellow and lives in the western US. He loves habaneros.
September 29th, 2010 at 5:59 pm
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September 29th, 2010 at 7:45 pm
I think calling this habitable is a bit wishful thinking. It doesn’t rotate enough so you have one hot side and one cold side. I have a hard time believing we could live on it let alone any significant life evolving. But 20 light years isn’t that far. We could probably send a probe there within a person’s lifetime were we inclined to spend the money. (Not that I think it would be worth it given our current level of technology)
September 29th, 2010 at 7:51 pm
it worked in the wheel of the winds.
September 29th, 2010 at 7:52 pm
Actually I’ll take that back. I thought Daedalus would go faster than it does. Plus ICF fusion isn’t quite up to snuff even today. So 20 light years is about a 500 year trip in a best case scenario right now.
September 29th, 2010 at 11:26 pm
According to recent simulations it seems tidal lock is not a big issue. The night side doesn’t freeze, even if the atmosphere density is only a few percent of ours.
Not only Gliese 581 is close, but it is also one of only few actively monitored stars in our neighborhood. That we find a habitable planet so soon means the total number must be huge. Vogt puts the value to “few tens of percents”, but even a fraction of that could mean billions of potentially habitable planets in the Milky Way.
Not that we didn’t expect that…
The original paper is here. Interesting read.
September 30th, 2010 at 5:01 pm
If planets in habitable zones are common, the Fermi paradox becomes even more glaring.
My guess is that there are bottlenecks at both complex life and civilization capable intelligence and phenotypes.
October 1st, 2010 at 6:46 pm
@5. Kullat Nunu,
Interesting to hear that (tidal locking matter). I’ve felt that the whole concern over head distribution due to tidal locking was way overstated. As long as the planet has an atmosphere that’s a pretty good way to move heat around. Even better is if it has large oceans. The weather could be severe but life could adapt.
Suggesting that the only potentially habitable zone is on the fringe of day/night is even more silly.
And of course, if there’s no atmosphere, no water, then life as we know it probably isn’t possible at all. But that would be due to the lack of atmosphere and water, not due to temperature extremes.