Astronomers Find Smaller Extrasolar Planets

SABME writes "NASA has announced the discovery of a new class of extra-solar planets. Here's a link to the NASA news release. These planets are only 10-15 times bigger than Earth; how far off are we from discovering Earth-sized planets orbiting other stars? Future NASA missions aimed at broadening these discoveries include Kepler, the Space Interferometry Mission and the Terrestrial Planet Finder. More info available at NASA's Extrasolar Planets webiste.

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Comments

It will be a long time . . .

[kalidasa]

Before they find a genuinely earth-like planet with this technique - with the radial velocity technique you find big close planets first, later big distant planets and medium-sized close planets, etc., and small close but not too close planets last. Not a criticism of the astronomers; it's amazing that they can find even a very close Neptune-sized planet with this. . .

Re:why does size matter?

[stevelinton]

Planets much larger than Earth will inevitably be either

a) much hotter than Earth (which is the case with these ones, I think)

or

b) mostly made of hydrogen and helium, like Jupiter, Saturn, Uranus and Neptune

At our temperatues, a massive planet would captuse lots of hydrogen and helium from the initial nebula and never lose them.

In either case, no life remotely like us could exist. Of course one cannot rule out life based on some exotic chemistry, but the absence of evident life on Mercury or any of our own gas giants is a small piece of negative evidence.