Astronomers Claim Discovery of Earth-like Planet 225
Raver32 writes "A team of astronomers announced they have discovered the smallest and potentially most Earth-like extrasolar planet yet. Five times as massive as Earth, it orbits a relatively cool star at a distance that would provide earthly temperatures as well, signaling the possibility of liquid water. 'The separation between the planet and its star is just right for having liquid water at its surface,' says astronomer and team spokesperson Stephane Udry of the Observatory of Geneva in Versoix, Switzerland. 'That's why we are a bit excited.' But researchers do not yet know if the planet contains water, if it is truly rocky like Earth, which might make it hospitable to life as we know it, or whether it is blanketed by a thick atmosphere. 'What we have,' Udry says, 'is the minimum mass of the planet and its separation" from its star.'"
Interesting find. (Score:3, Interesting)
I wonder how long before we can verify an earth like extrasolar planet?
As more of these are found we may be able to plug more data into drake's equation [wikipedia.org]
Re:TFA (Score:3, Interesting)
Oh, they just don't like me. I've learned to deal with it.
Re:Interesting find. (Score:5, Interesting)
Since Drake's equation needs to know the proportions of stars with planets, it would require us to have known negative results as well as known positives in order for it to give any meaningful results.
At the moment, we can say there are a few hundred planets, out of maybe a few thousand stars that we've scanned, but for the stars where we haven't found anything, we don't know for sure whether that's because there isn't anything there, or because we just aren't looking hard enough.
Re:5x mass = 5x gravity (Score:4, Interesting)
Plus you can take into account all the other advantages life on Earth has had to make it possible:
- In a solar system with a large gas giant, which helps keep catastrophic impacts with asteroids and comets from happening too often
- Has a large satellite, which may help stabilize climate
- Is in a quiet part of the galaxy, and is not too near other stars, avoiding interactions with other stars/gamma ray bursts/etc.
What's the eccentricity of the orbit? (Score:4, Interesting)
That's kind of important, I would think.
Re:5x mass = 5x gravity (Score:3, Interesting)
These points, among others, are made by authors Ward and Brownlee in the book Rare Earth
Long story short, complex life as it exists here on Earth is the result of a long series of very happy accidents. The odds against it happening elsewhere are ... well ... astronomical.
Re:5x mass = 5x gravity (Score:3, Interesting)
In fact, I would argue that from a human sized point of view, it contains an astronomical number of elsewheres.
Re:5x mass = 5x gravity (Score:3, Interesting)
Planetary Technonics (Score:3, Interesting)
Assuming that the density is a little bit less than the Earth (more like the Moon or Mars) and this "Super Earth" is thus larger by a sizable fraction..... what is the geological environment of a planet such as this like?
Since the interior heat of this planet has less surface area in proportion to its volume, internal heat from its formation and nuclear decay from heavy elements (like Uranium) would therefore cause a much larger interior heat sink... and causing substantially more techtonic activity and a great many more volcanoes.
Using Mars as a comparator here as well, Mars is smaller than the Earth, and geologically dead, with fewer but much larger volcanoes. Is it reasonable to assume this planet... if it had a rocky "surface", would literally be littered with smaller volcanoes over nearly all of its surface with much smaller "continents"?
Assume that the age of this planet is roughly similar to that of the Earth and that heavy metals (heavier than Iron) in its formation are roughly proportional to what we find on the Earth.
I just don't find that this would be all that pleasant of a place to be at, and the nearly constant volcanism would IMHO kill off nearly any attempt to colonize this planet with life.
It certainly would be a weird planet to look at though.
Re:Except, I don't think that is actually true. (Score:2, Interesting)
Re:5x mass = 5x gravity (Score:3, Interesting)
In this paper [arxiv.org] there are theoretical relations between planet radius and mass for a wide range of possible planet compositions. These are computed using equations of state that are largely determined from laboratory experiments.
Anyway, for an Earth-like composition (~67% rock, 33% iron), a 5 M_earth planet would have a radius of ~1.5 R_earth yielding a surface gravity that is ~2.2 times greater than that of the Earth (such a planet is not incompressible, so the density is slightly higher for a greater mass).
For a pure iron planet, the radius would be only 1.2 times that of the Earth and the surface gravity would be quite high (3.6 times the Earth's).
For a pure rock planet, the radius would be 1.7 times that of the Earth and the surface gravity would be 1.75 times that of the Earth.
For a pure "water-world" (say a scaled up version of some of the icy satellites orbiting the outer planets), the radius would be ~2.5 times that of the Earth and the surface gravity would be 0.8 times that of the Earth (i.e. less surface gravity than the Earth!).
Point is there is a fairly significant range in possible radii and thus a significant range in the possible surface gravity.
Re:Pointing a Big-Ass Telescope (Score:3, Interesting)
Re:You're making that up (Score:1, Interesting)
Well, it is proportional to mass, it just also happens to be inversly proportional to the square of the radius.
Solving for x.
x*G*m_e / r_e^2 = G*5m_e / (1.5r_e)^2
x = 4 / 2.25
so about 1.78 times Earth gravity