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:Earthlike?

[scheming daemons]

By "earth-like" they meant that it is terrestrial, not a gas giant (a la Jupiter or Saturn).

Until now.. they hadn't found a planet in another star system that was

A) terrestrial (solid, with a rocky surface) B) farther than 0.15 AU from its star.

This planet is 2.5 AU from it's star and it is not a gas giant. That's what makes it "earth-like".. in the way that mercury, venus, mars, and pluto are "earth-like".

Until now.. no such planet had been observed in another star system.

All of this is in TFA.

Re:Wait...

[mrsev]

"at -220 C .......so the chance of finding life on this planet is essentially zero."

I get fed up with people saying this. Our data set for planets that can support life is 1. We have no idea what "other" lifeforms can survive. Pretty much everywhere we look on earth we find life.

We find it at +120C at several thousand atmospheres of pressure next to thermal vents.

We find it at -40 C under meters of ice.

We find it living in our stomachs at a pH of less than 2.0.

We find it making a living from cleaning the insides of a sharks mouth.

I am sure that if you go into the charred remains of Reactor core number 4 chernobyl you will find plenty of life.

All you need for life is some form of energy that can be harnessed and some raw materials to use. There is no justification for saying that we should look for life at 300 kelvin and 1 atmoshphere pressure and 20% oxygen. For the report on a "scientific" article it is just lame speculation dressed as informed fact.

Surface Temp of -220 C

[aquatone282]

" . . .has a surface temperature estimated at -220 C which means . . . the chance of finding life on this planet is essentially zero."

Obviously these researchers have never met my ex-wife.

Re:Basic thermodynamics

[Jim_Callahan]

Uh, melting point varies with pressure and a couple other factors that depend on your PVT model. You can melt pretty much any material if you set the conditions correctly, regardless of wether the decomposition temperature is below the MP at 1 atm or not. The liquid phase may not be very accessible, but it's always there.
 
Also, you need a better example, since Sucrose (the molecule people mean when they say 'sugar' without a qualifier) has a MP of 191 degrees centigrade at 1 atm, i.e. it has a viable liquid phase pre-decomposition. Perhaps you're thinking of Glucose or Ribose?
 
You could make an argument that 'frozen liquid' would refer to an amorphous (non-crystalline/glassy) structured solid only, as these result from a skipping of the phase formation bit of solidification to just lock the structure of the liquid into solid form. However, I think it's more likely that the writers of the article just skipped the materials phase of their education, locking the structure of their brains into a void-filled physics-oriented glass. Or they just, you know, made the intellectual equivalent of a typo. Whichever.

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.