Scientists See Far-Off Solar System Much Like Ours

Nov. 6, 2007 — -- Far away, around a star in the constellation Cancer the crab, scientists say they have discovered new evidence that we may not be alone.

A group of scientists working in Hawaii and California reported today that the star 55 Cancri has a complete solar system -- five planets, in almost circular orbits, at least one of which seems to be in the star's "habitable zone," where temperatures are likely to be right for liquid water to exist.

It has been more than a decade since astronomers found the first so-called "exoplanets" -- planets orbiting other stars -- and the total count is now more than 250.

But most of them were vastly larger than the Earth and followed lopsided, elliptical orbits. If they orbited close enough to their host stars to be warm, they would alternately fry and freeze -- not the best conditions for life to take root.

"This discovery of the first-ever quintuple planetary system has me jumping out of my socks," said Geoff Marcy, an astronomer at the University of California at Berkeley who is one of the world's leading discoverers of far-away planets. "We now know that our sun and its family of planets is not unusual."

Marcy and other scientists have been scanning the heavens, openly hoping to find planets like Earth.

"This discovery shows that our Milky Way contains billions of planetary systems," said Marcy.

The scientists who reported the find today said they have been watching 55 Cancri for 18 years, using the Keck Observatory in Hawaii and the Lick Observatory in California as part of a project funded by NASA and the National Science Foundation.

The star is 41 light years away, more than 240 trillion miles. Because of the great distances, they could not directly see the planets, but they could watch the star wobbling, ever so slightly, because of the gravity exerted on it by the planets as they orbited.