Astronomers find system with five planets

By Maggie Fox, Health and Science Editor Tue Nov 6, 3:39 PM ET

WASHINGTON (Reuters) - NASA scientists said they discovered a fifth planet orbiting a star outside our own solar system and say the discovery suggests there are many solar systems that are, just like our own, packed with planets.

The new planet is much bigger than Earth, but is a similar distance away from its sun, a star known as 55 Cancri, the astronomers said on Tuesday.

Four planets had already been seen around the star, but the discovery marks the first time as many as five planets have been found orbiting a solar system outside our own with its eight planets, said Debra Fischer, an astronomer at San Francisco State University.

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"The star is very much like our own sun. It has about the same mass and is about the same age as our sun," Fischer told reporters.

"It's a system that appears to be packed with planets."

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They said 55 Cancri is 41 light-years away in the constellation Cancer, a light-year being the distance light travels in one year -- about 5.8 trillion miles.

The newly discovered planet has a mass about 45 times that of Earth and may resemble Saturn, the astronomers said.

HARBORING LIFE?

It is the fourth planet out from the star and completes one orbit every 260 days -- a similar orbit to that of Venus.

"It would be a little bit warmer than the Earth but not very much," said Jonathan Lunine, a planetary scientist at the University of Arizona.

The planet is 72 million miles from its star -- closer than the Earth's 93 million miles, but the star is a little cooler than our own sun.

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"This discovery of the first-ever quintuple planetary system has me jumping out of my socks," Marcy added. "We now know that our sun and its family of planets is not unusual."

They have posted images of what the planets may look like on the Internet at http://www.nasa.gov/audience/formedia/telecon-20071106/.

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