Narrator: This is Science Today. Earlier this year, an international team of astrophysicists discovered a distant, icy planet five times the size of Earth. The smallest extrasolar planet revealed outside of our solar system was found using a technique called microlensing that is based on an idea Albert Einstein came up with 70 years ago. Astronomer Ken Cook of the Lawrence Livermore National Laboratory, who was part of the group that made the discovery, says this happens when a foreground star passes very close to the line of sight of a more distant star. This creates a ring-like image.
Cook: Now, this ring is so small on the sky that we can not tell it's a ring – all that we can tell is that suddenly the star is brighter. And when planets get near the ring, it perturbs the light coming, so it causes a little bump in the light curve that we see. As soon as this star moves off the line of sight, this star goes back to being dimmer and its normal self.
Narrator: The new Earth-like planet, made of rock and ice, orbits a parent star every ten years at three times the distance from Earth to the sun. For Science Today, I'm Larissa Branin.