A Million Questions About Habitable Planet Gliese 581g (Okay, 12)

[Swede]

A newfound Earth-sized planet discovered in the habitable zone of a nearby star looks very promising for the possibility of extraterrestrial life, but many unknowns remain.

The planet, Gliese 581g, is one of two new worlds discovered orbiting the red dwarf star Gliese 581, which now has a family of planets that totals six.

Here is SPACE.com's look at what scientists know so far about the intriguing world, as well as a few questions that don't quite have answers yet. Consider it a new entry into Earth's own hitchhiker's guide to the galaxy:

http://www.space.com/scienceastronomy/habitable-alien-planet-gliese-581g-facts-101001.html

[Blues Heron]

1. How big would Gliese 581 appear from the surface of this planet

compared to how big our sun looks for us? It's got to be bigger right cuz it's so close, even taking into account that the red dwarf is smaller than our sun. Big old glowing ember of a sun as big as our full moon maybe? hmmm

[laconicsax]

2. Both our sun and moon are about half a degree wide viewed from the Earth.

The moon the same degree smaller from the sun as it is closer to us, so both sun and moon appear the same size from Earth.

Gliese 581 is about 3.5 times the smaller than sun (by radius) but is 6.67 times closer to Gliese 581g. I think that means Gliese 581 would would appear about twice as big from the surface of the planet as the sun/full moon from Earth.

[Blues Heron]

3. Thanks! can't believe I forgot about the moon/sun apparent size equivalence!

Thanks for doing the math on this one. I'd love to see that huge sun twice as big as our sun/full moon!

[thereismore]

6. Nice. I like your avatar. The "A" is like a modern scarlet letter. nt

[laconicsax]

9. Thanks.

http://outcampaign.org/

[muriel_volestrangler]

4. An interesting bit about climate conditions - fairly stable, an astronomer says

Since we were speculating here earlier that it might be pretty rough:

Researchers also know that the planet is tidally locked to its star. That means one side experiences eternal daylight, and the other side experiences unending darkness. Such a locked configuration helps to stabilize the planet's surface climate, Vogt said.

3-D global circulation models have shown that the temperature differences on the day and night sides of the planet would not be enough for water to either freeze or boil off. They also suggest that the atmospheric circulation and wind patterns would be relatively benign.

[wuvuj]

5. The IGC will NOT allow....

...humans to visit or colonize this planet. Humans have been given a "pest species" status by the IGC. We thank you for your support.

[txlibdem]

10. They must mean the atmosphere at the surface

When it gets over 120 degrees in the Sahara with a 12/12 sunlight/dark pattern I just can't imagine the surface temps on the "daylight" side of Gliese 581B. And the opposite side of the planet being bathed in perpetual darkness would seem to me to allow temps there to plummet to unknown depths. The only way I can see any hope of surface temperature equilibrium on the surface would be a series of jet streams to distribute the heat. That should create tornadoes/hurricanes, assuming there is an atmosphere.

[Phoonzang]

7. It occurs to me that if there were a space-faring species inhabiting the Gliese 581 system

they would be able to get from planet to planet fairly easily. No six-month journeys to the nearest planet like in a Yellow Dwarf system. Look at how close the planets are to each other:

[muriel_volestrangler]

8. Against that, they'd have a bigger gravity well to get out of

since Gliese 581g weighs quite a bit more than the earth.

And, of course, six months might not be a problem to them. They might have a slower metabolism, or a voluntary 6 month sleep period, and so on. Or just 1 month might be a real problem to them, because they live much faster than we do.