Narrator: This is Science Today. Astronomers at the University of California, Berkeley may be able to provide more information about how solar systems form. Barry Welsh, a project manager at the Space Sciences Laboratory, says there are many theories.
Welsh: What I can do is at least tell you what's left over in the clearing out phase of planetary systems.
Narrator: That's because Welsh and his colleagues don't actually look for planets - they look for what's left over after planets have been formed.
Welsh: The sort of things that are left over from when you make planets is a lot of dust, a lot of rocks and things called comets - or planetesimals. These are sort of, failed planets, or what's left over.
Narrator: By looking for this cosmic debris of sorts, Welsh found two nearby stars with planetesimals.
Welsh: The significance is that if the comets that I'm viewing look similar to the comets that we see in our own solar system, then you can infer that the planets that are in these new solar systems are pretty similar to the ones in our own.
Narrator: For Science Today, I'm Larissa Branin.