Wednesday, May 18, 2011

Habitable Planet Found?

French scientists have found a planet that they say is most likely habitable. Gliese 581d, about 20 LYs distant, circles a red dwarf star and has a stable atmosphere, comfortable temperatures, and a surface covered in liquid water.

Though Gliese 581d is about the size of two Earths and masses upwards of six times Earth mass scientists consider it to be a good candidate for habitability because of it's rocky surface, ability to maintain a robust stable atmosphere and receive enough energy from the red dwarf to maintain large bodies of liquid water.

Even so it is not likely to be a vacation spot. From the article:
  • That's not to say it would necessarily be a pleasant place to live, though. Gliese 581d probably depends on a significant greenhouse effect to keep itself warm since it gets relatively little energy from its star. The atmosphere is mostly CO2, and while you'd get clouds and warm rain and oceans and stuff, the surface itself would be "in a perpetual murky red twilight."
The scientist's models also suggest that Gliese 581d may be tidally locked.

Cosmos article Dvice blog article


Jay said...

Ah, a new vacation spot!

Dave Tackett said...

"in a perpetual murky red twilight." So it's one big red light district like Amsterdam and Hamburg? (Sorry couldn't resist)

Seriously it's very cool, though this one has went back and forth for so long, I won't be surprised if someone publishes a paper trying to debunk the latest consensus.

Interestingly, plants tend to grow
"tall and spindly" under pure red light, which might make up for the higher surface gravity and allow them to grow to Earth plant sizes (pure speculation of course).

Charles said...

So I would weigh 1200 lbs? If I were at 200Lbs on earth. 6 times mass.

Beam Me Up said...

Hey Charles, that is a GREAT question.
My simple thoughts on this are that the "weight" would depend on how close you are to the mass. I know that came out garbled, but what I mean is if the mass was the same size as Earth but massed 6 times as much then yeah, you would, but the trick here is that not only is is more massive but twice as big, so that places you further away. So my guess is that you would weigh 3x instead of 6x.

Has my math fallen down here guys?

Beam Me Up said...

Dave....but wouldn't the greater gravity preclude that kind of growth?
Tall and Spindly might be a relative kind of thing. What plants came to mind? I think trees would be a strange thing there. They could still be straight, but the trunks would have to be massive. If trees are going to be tall they are going to need a very different capillary action, because water is going to rise less than 33 inches. And branches, what, short and thick and I can't see leaves working at all unless they scaffold with something much more robust. what else?

Dave Tackett said...

Most of the estimates for surface gravity (if it has roughly the same density as Earth) fall between 1.8g and 2.0g. Not my calculations, but this calculation from Physicsforums seems correct.

"The radius is indeed proportional to the cube root of the mass so if r = r_earth * M^(1/3) then
g will be g_earth * M / (M^(1/3))^2 = g_earth*M^(1/3) and everyone will be 1.91 times heavier."

"wouldn't the greater gravity preclude that kind of growth?" That's HUGE, fascinating question Paul. Will the surface gravity be enough to prevent the tendency of plants to grow tall in red light? If so, will they be as squat as they would likely be under the same gravity but yellow light? Or will they evolve completely differently? A lot of fun speculation, but not really testable since any life there would have had a completely different evolutionary history than Earth plants.

Beam Me Up said...

Dave then M is mass right? So wrapping my head around this we have G cube root but my algebra is abismal M^? Cube root? I thought cube root was N3 (crap no superscript!)

You got to give me credit though, I did a Babylonian guess to get to 3x. Not bad for the barely educated!

Charles said...

So superman born under red sun. Lets not bring any thing back from there it might just fly around and eat us!!! :)

Beam Me Up said...

yeah and if its like would you cut it?! Just the possibility of "look! up in the sky!"

John said...

Yes, it's only a matter of time before we find visual-electronic evidence of a habitable world... The funny thing is... It'll probably already be inhabited once we find it, But we won't know for many many moons.

Beam Me Up said...

i can remember someone saying that and the thought was that once they get to that level to communicate they probably destroy themselves. So when we hear them....they are already long dead. Hell thats even too depressing even for me!