Planet discovered in an Earthlike system

WALNUT CREEK, Calif. (MCT) — A record-setting fifth planet discovered orbiting a star 41 million light years away suggests there may be many populous planetary systems like our own, some of which could harbor life.

The new planet is about 45 times the mass of Earth, scientists said Tuesday, and is situated at a similar distance from its star, which is known as 55 Cancri and is part of the constellation Cancer. It has a circular orbit that takes 260 days.

The planet is the fourth in distance from the star, and though it resides within the habitable zone where mild temperatures would allow water to exist in liquid form, it is too big and gaseous to host life. But similarities between the 55 Cancri system and our own solar system have astronomers intrigued about the possibility that smaller Earthlike planets or moons could be found there someday.

"The host star of these planets is very much like our own sun," said astronomer Debra Fischer of San Francisco State University, a member of the team that discovered the planet. "It appears to be a system packed with planets."

The five planets span a similar distance from the star as the eight planets in our solar system. The outermost planet resembles Jupiter, though larger, while the innermost is similar to Neptune.

"Architecturally, this new system is reminiscent of our own system, albeit souped up," said UC Berkeley astronomer and co-discoverer Geoff Marcy.

Small, rocky planets like Earth are beyond the detection limits of current technologies, but NASA has plans to someday launch telescopes into space that will be able to photograph and analyze these planets and assess their ability to sustain life.

The new planet's discovery took 18 years of careful measurements by some of Earth's most powerful telescopes, including the Lick Observatory on Mount Hamilton, and consistent funding from NASA and the National Science Foundation. Astronomers used the wobble of the host star caused by the gravitational tug of its orbiting planets to deduce their existence.

Because the outermost planet, which resembles Jupiter, has a 14-year orbit, it took as many years plus a few more to determine that a fifth planet was affecting the wobble.

"This discovery of the first quintuple planetary system has me jumping out of my socks," Marcy said. "We now know that our solar system is not unique. We strongly suspect that many of these planetary systems harbor Earthlike planets."