Potentially Habitable Planet Discovered (opens in new tab)

In a couple centuries, (hopefully) it'll be a non-issue. Who knows? The important thing is that we actually found something only theory foresee.

Assuming this particular news really did it, because I'm certain I've read similar headlines in the past.

Really, if you want to cross inter-stellar space in any kind of reasonable time - O(human lifetime) - you need to go faster. Possible solutions are: solar sail or new kinds of ion thruster. Both of these impart a very small force (and hence acceleration) for an exceedingly long time, resulting in very high velocities. Your target speed is about 10% of c. In the case of the solar sail it receives momentum from sun for ~ 50% of distance (assuming similar-sized star to our sun), and then is braked by the momentum from the target star for the rest of the journey.

Problem with solar sail is it needs to be GIGANTIC, and composed of materials stronger and lighter than those available today. Additionally force from sunlight is proportional to 1/r^2 so your acceleration decreases with distance.

So, nuclear powered ion thruster is probably the answer. But, obviously, this kind of project is expensive. And either way, you need living quarters for an entire society to live and reproduce.

http://www.google.com/#q=21+light+years+%2F+35%2C000+miles+p...

(21 light years) / (35 000 miles per hour) = 402 369.978 years

That ship would get there in 25 years or so, so most of us would live to see the reply on its telemetry around the time our grandchildren are our age.

Really, this would be: 35,000 mph / (60 minutes per hour) / (60 seconds per minute) = 9.72 miles per second.

Then just decrease the distance traveled by a factor of 60, so instead of 386 billion miles traveled by V2, it would be about 6.4 billion miles.

Following up on some of the references, it does seem like the long-standing belief is that being a certain distance from the parent star strongly predisposes a planet to tidal locking: "planets close enough to their parent star to possess liquid water on their surfaces (the conventional HZ, below) should be tidally locked (Dole, 1964)," (Scalo et al, 2007); "For stellar masses below 0.6 MSun, exoplanets orbiting in the HZ become tidally locked within the first billion years (e.g., Kasting et al., 1993; Grießmeier et al., 2004, 2005)." (Lammer et al, 2007).

EDIT: D'oh! The OP is talking about 581 g, not d. Serves me right to just grab the first article I see on arXiv about a planet in the Gliese 581 system.

http://en.wikipedia.org/wiki/Tidal_locking

which gives a timescale for how long it takes for a body to become tidally locked to the body it orbits. I haven't plugged in the numbers for this planet, but I'm gonna assume it winds up being much shorter than the age of the star.

This is the first time I've seen a story about an actual earth-like (with fairly loose parameters) planet that is roughly in the life-zone! Usually headlines that say "earth-like planet discovered!" involve either a frozen rock orbiting way outside of its sun, or a burning pebble right next to it.

However important this particular planet is, I think it's a first as far as fairly plausible life candidates go. Here's to more!

You can expect to hear this story once more: the first time we discover a planet in the habitable zone which isn't probably tidally locked. In another ten years we'll probably know dozens of habitable-zone planets and nobody will care about 'em much.

Still, what are you expecting to happen? With current technology all we can do is sit here and watch the star wobble. We can't get a direct image of the planet, we can't determine its radius, we can't determine its composition, or whether it has an atmosphere, and we certainly can't get there.

Actually the first time a transiting potentially habitable planet (ie one whose orbit takes it across the face of its star as seen from Earth) we will be able to determine its radius and perhaps within our lifetime its atmospheric composition (current instruments are almost but not quite good enough to get a proper absorption spectrum of a transiting exoplanet). So that's something to look forward to.

Hundreds of planets like Gliese 581g will probably be found in the next three years. As we slowly build more and bigger telescopes, we'll gain more and more information about them. This is a process that takes decades.

So don't expect "something to happen" tomorrow because of this discovery. Something should happen in your mind immediately, but the real and physical repercussions of this discovery are slow and expensive.

If you want them to speed up, you should lobby your government to increase their funding, or perhaps donate to some of these projects yourself :)

Here on Earth, life gets its energy from soaking up solar energy, or from eating things that have been soaking up solar energy, or from eating things which have eaten things which.... you get the idea. The sole exception is at deep-sea geothermal vents, where you can pick up energy from the thermal gradient. On Gliese 581g, there's huge amounts of energy to be picked up just from the constant flow of energy from hot side to cold side, so I'd expect lifeforms to somehow be tapping into that.

On the other hand, if there's both sufficient water AND enough air for life as we know it on our planet's surface (excluding the extremeophiles like the flora living in Grand Prismatic Spring for the moment), the terminator wouldn't be nearly as clear as it is on Mercury, which has no atmosphere. Oceans of air and water would help to distribute heat throughout the world, much like they do here on Earth.

Given an earth-like atmosphere, the wind at the terminator would be a fairly constant 20mph from the sunward side to the shadowed side. Elsewhere, it would be slower. The upper atmosphere would circulate much faster than the rotational period of the planet, spreading the heat out pretty evenly over the planet.

Given an earth atmosphere, and the same heat from the sun as the earth, it would be about 25F on the shadow side pole, and 135F on the light side pole.

Of course, tectonics on a tidally locked planet are another thing, and if its surface has fused its atmosphere is probably chock full of H2SO4.