New planet system discovered

WASHINGTON (AFP) – US astronomers announced Thursday the discovery of a solar system they say bears similarities to our own and includes three planets orbiting a sun 41 light years away.

Astronomers said they have identified an extrasolar planet orbiting the star, named 55 Cancri, at about the same distance Jupiter orbits the sun.

"Today we are announcing the discovery of a planet that for the first time resembles a planet in our solar system," Geoffrey Marcy, an astronomy professor at the University of California at Berkeley, told a NASA press conference here,

"All other extrasolar planets discovered up to now orbit closer to the parent star, and most of them have had elongated, eccentric orbits. This new planet orbits as far from its star as our own Jupiter orbits the sun," Marcy said.

The planet is more than 500 million miles from its sun, a comparable distance to that between Jupiter and our sun. And it takes 13 years to complete a revolution as opposed to Jupiter’s 11.86 years, although it is 3.5 to 5 times bigger than Jupiter.

A second planet, a gaseous planet similar in size to Jupiter, revolves around 55 Cancri at one-tenth Earth’s orbit taking only 14.6 days to circle the star.

Scientists have not yet ruled out finding an Earth sized planet between the Jupiter-sized and Jupiter-distanced planets orbiting 55 Cancri, which is five billion years old. The discovery comes after 15 years of studying 55 Cancri.

At the same press conference Marcy and his colleague Paul Butler, of the Carnegie Institution in Washington, announced the discovery of a total 15 new extra-solar planets, bringing the total number of known planets outside our solar system to more than 80.

One of the new planets found circle the star HD49674 in the Auriga constellation at about one-twentieth Earth’s orbit, although it is 40 times the size of Earth.

"We haven’t yet found an exact solar system analog, which would have a circular orbit and a mass closer to that of Jupiter. But this shows we are getting close," Butler said.

"I think we will be finding more of them among the 1,200 stars we are now monitoring," he said.

"The first planet outside of our solar system was discovered only six years ago," Marcy said, underlining the rapidity with which this field of astronomy has advanced.

"The existence of analogs to our solar system adds urgency to missions capable of detecting Earth-sized planets," said Dr. Charles Beichman, NASA’s Origins Program chief scientist at the agency’s Jet Propulsion Laboratory in Pasadena, California.

"This planetary system will be the best candidate for direct pictures when the Terrestrial Planet Finder is launched later this decade," he said.