SPACE: It's out there ... and it's like us
Sun | Nation & World
* For the first time, scientists have confirmed that there is a solar system like ours.
SAN FRANCISCO - For the first time, there is clear evidence that a solar system other than our own exists, researchers said Thursday.
Three huge planets are spinning around the star Upsilon Andromedae 44 light years from Earth in our Milky Way galaxy, San Francisco State University researchers said at a news conference.
Their presence indicates that many of the Milky Way's 200 billion stars are likely to have planetary systems.
"It implies that planets can form more easily than we ever imagined, and that our Milky Way is teeming with planetary systems," said Debra Fischer, one of the researchers.
The researchers began their search for planets 12 years ago. They and their colleagues are responsible for finding 14 of the 20 planets known to exist outside the Earth's solar system.
However, those planets were single bodies surrounding a star. This is the first time multiple planets around a star have been found.
The innermost of the three planets, spotted in 1996, has at least 75 percent of the mass of Jupiter and is very close to its sun, orbiting once every 4.6 days. Jupiter is the largest planet in the solar system, 318 times the size of Earth.
The middle planet is twice Jupiter's mass and orbits the star every 242 days from a location about as far as Venus from the sun. The outer planet has the mass of four Jupiters and orbits its star every 312 to four years. It is more than twice as far from its star as Earth is from the sun.
Earthlike planets are unlikely to be found in such systems, the scientists said, because the forces generated by huge Jupiterlike planets moving in elliptical rather than circular orbits would kick smaller planets out into oblivion.
"Now, we have a multiple system, maybe a Rosetta stone to help us understand a lot of these weird planets we're finding," said R. Paul Butler by telephone from the Anglo-Australian Observatory in Epping, Australia.
The Rosetta stone is an ancient inscription in three languages that allowed scientists to decipher Egyptian hieroglyphics.
Upsilon Andromedae is easily visible with the naked eye, although it is currently behind the sun and will not be seen until June.
The planets were discovered using a method that measures their gravitational pull on their star, not by direct observation. Planets' gravity tugs on their stars, causing them to wobble slightly. By examining the star's ultraviolet light transmissions, astronomers can calculate back-and-forth shifts in the ultraviolet wavelengths. A larger wobble indicates the orbiting planet is large.
"I am mystified at how such a system of Jupiterlike planets might have been created," said Geoffrey Marcy, professor of physics and astronomy at San Francisco State.
"This will shake up the theory of planet formation."
Alex Wolszczan, an astronomy professor at Penn State University, called the discovery an important step toward understanding the cosmos.
"It has been anticipated and awaited by the scientific community. It's nice to see it's finally happened," he said. "What I get right away from this particular discovery is that it emphasizes even more how different those systems are from our own."