Since the online citizen science project Planet Hunters launched last December, 40,000 web users from around the world have been helping professional astronomers analyze. the light from 150,000 stars in the hopes of discovering Earth-like planets orbiting around them

Are we alone, or is there life elsewhere in the universe? That is the fundamental question astronomer Dr. Debra Fischer attacks in her work as a "planet hunter" at San Francisco State University.

Sydney, Australia -- A comparison of 754 nearby stars like our sun -- some with planets and some without -- shows definitively that the more iron and other metals there are in a star, the greater the chance it has a companion planet."Astronomers have been saying that only 5 percent of stars have planets, but that's not a very precise assessment," said Debra Fischer, a research astronomer at the University of California, Berkeley.

By Robert Sanders, Media RelationsAn orb by any other name: Debate over what constitutes a planet is far from settled BERKELEY -– Ask any kid how many planets are in our solar system, and you'll get a firm answer: nine.But knock on a few doors in Berkeley's astronomy department, and you'll hear, amid the hemming and hawing, a whole range of numbers.Professor Gibor Basri, who plans soon to propose a formal definition of a planet to the international body that names astronomical objects, argues that there are at least 14 planets, and perhaps as many as 20.