STORY:
The rocky planet known as "GJ 436T" has a mass five times the size of Earth. This makes it the smallest extrasolar planet identified so far. It is located 30 light years from earth in the constellation of Leo.

It was discovered by Spanish astronomers led by Ignasi Ribas. Their detection method was to analyze distortions in the orbit of another larger planet.

[Ignasi Ribas, Investigation Scientist]:
"In this case we don't use the perturbations on a star but we use the perturbations on another planet that was already known in the system. That planet has an eccentric orbit, an elliptical orbit instead of being circular which is a surprise, was a surprise."

Mr.Ribas is hopeful of finding soon earth-like planets with this new technique.

[Ignasi Ribas, Investigation Scientist]:
"This is a step in this direction, into finding more and more earth-like objects. Probably in the near future, less that decades we will have the first earth twin probably already detected."

Mr. Ribas says the new planet is uninhabitable due to the distance that separates it from its star. Apparently, to sustain life a planet must have a mass similar to that of the earth, and a similar orbital distance from its star as that of the earth from the sun.