WASHINGTON -- The more astronomers look for other worlds, the more they find that it's a crowded and crazy cosmos. They think planets easily outnumber stars in our galaxy, and they are finding them in the strangest of places.
And they have only begun to count.
Three studies released Wednesday demonstrate an extrasolar real estate boom. One study shows that in our Milky Way, most stars have planets.
And since there are a lot of stars in our galaxy -- about 100 billion -- that means a lot of planets.
"We're finding an exciting potpourri of things we didn't even think could exist," said Harvard University astronomer Lisa Kaltenegger, including planets with twin suns and a mini-star system with a dwarf sun and shrunken planets -- not unlike Luke Skywalker's home in "Star Wars."
"We're awash in planets where 17 years ago we weren't even sure there were planets" outside our solar system, said Kaltenegger, who wasn't involved in the new research.
Astronomers are finding other worlds using three techniques and peering through telescopes in space and on the ground.
Confirmed planets outside our solar system, called exoplanets, now number well over 700; still-to-be-confirmed ones are in the thousands.
NASA's new Kepler planet-hunting telescope in space is discovering exoplanets that are in a zone friendly to life and detecting planets as small as Earth or even tinier. That's moving the field of looking for some kind of life outside Earth from science fiction toward real science.
One study in the journal Nature this week figures that the Milky Way averages at least 1.6 large planets per star -- likely a dramatic underestimate.
That study is based on only one intricate and time-consuming method of planet hunting that uses several South American, African and Australian telescopes. Astronomers look for increases in brightness of distant stars that indicate planets between Earth and that star.
That technique usually finds only bigger planets and is good at finding those farther away from their stars, sort of like our Saturn or Uranus.
Kepler and a ground-based telescope technique are finding planets closer to their stars. Putting those methods together, the number of worlds in our galaxy is probably much closer to two or more planets per star, said the Nature study author Arnaud Cassan of the Astrophysical Institute in Paris.