Microlensing Uncovers Earth-Like Planet

smooth wombat writes "Using a new technique called gravitational microlensing, a team of astronomers have discovered the smallest Earth-like planet circling a star 20,000 light years away in the constellation Sagittarius. Unfortunately the planet takes ten years to circle the red dwarf and has a surface temperature estimated at -220 C which means it's just a larger version of Pluto so the chance of finding life on this planet is essentially zero."

Comments

Re:Wait...

[jc42]

How do we know there aren't certain forms of life for which -220C is like a warm, hunky-dory bath?

Actually, there are some good (but not conclusive) chemical reasons. Some of them came out in the recent discussions of why Titan might support life.

Now, -220C is abut 53K, which is pretty cold. Titan is about 94K, which doesn't sound much warmer to us, but it's actually nearly twice as "warm". At 94K, methane is a liquid, and it's also a solvent. It behaves much like water, though it's a non-polar molecule, so any biochemistry would be different from ours. In particular, methane is good at dissolving organic (i.e., carbon-chain based) compounds.

At 53K, methane is a solid.

All this is significant because it's reasonable to assume that complex life requires complex chemistry. At low temperatures, the only way known to do this is with carbon chains (though there has been speculation that at higher temperatures than ours, silicon could perform a similar role). And for biochemistry to work, most of the biochemicals should be in a liquid matrix, so they can move around and interact easily.

So a planet at 53K wouldn't be a very likely place to find complex chemicals with compex interactions. Everything interesting would be solid. At 94K, it's possible, with methane as the solvent substrate. At our body temperature, 310K, methane is a gas, but water is a liquid and a good solvent, so biochemistry works for us.

But you're right that this is all speculation, based on the only kind of life that we know. Science-fiction writers have contemplated life at other temperatures, but we have yet to find evidence of any.

A few years back, Robert Forward wrote a sci-fi novel, Camelot 30K, which is about the discovery of life on a Pluto-like planet in the Kuiper belt. The title comes from its ambient temperature, 30K, and the social order which is medieval. Being a good physicist, he explains at one point that the living creatures are all "warm blooded", with body temperatures arund 90K. This is so that their body fluids remain liquid. It turns out that they inhabit many of the Kuiper-belt planets, and have an interesting means of dispersal. Presumably they evolved a bit closer in, long ago, on a planet with temperatures somewhat higher. This may sound like a stretch, but our body temperature is about 30K above our planet's mean temperature.

Anyway, maybe some day we'll know more about what is possible. Maybe, as Forward imagined, we'll find out when we visit the outer reaches of our solar system. Or maybe not.

Most of the media attention to possible life is basically silly, and based on little more than speculation. If you want to be entertained by speculation without evidence, you're better off reading science fiction.