Fifth Planet Orbits 55 Cancri

The quest for life on other planets is one of humanity's obsessions, reflected in television shows like the X-Files. Astronomers, using funding from the National Science Foundation and NASA, have discovered a planet circling a nearby star that might have moons that can support life. The star is called 55 Cancri, found in the consetellation Cancer, some 41 light years from Earth. If you take your binoculars outside at night, the star is visible. No telescope is necessary. 55 Cancri is about the age of our sun.

This is the fifth planet discovered in 55 Cancri's orbit. Scientists spent years to discover the planet, using the sophisticated Doppler technique. The planet is discovered by examining the way that the parent star wobbles. The wobble is produced by the gravitational pull of the planet.

The new planet is probably similar to Saturn, and all Saturn type planets known to humans have moons. The moons of 55 Cancri would be in the zone, sufficiently far from the sun to promote life, but not too far away to prevent it, called the "habitable zone." Liquid water could, at this distance, exist on the surface in rivulets, puddles, and pools. The planet has a larger mass than Earth, about 45 times as much.

Debra Fischer, a San Francisco State University astronomer, says that the planet is a gas giant. Its rocky moons might have surface water.

Fischer, along with Geoff Marcy, of University of California, Berkeley, and a team of scientists made the discovery after long and hard work, observing almost 2000 stars. They used the W. M. Keck Observatory in Mauna Kea, Hawaii, and the Lick Observatory Shane telescope at Mount Hamilton, California, located to the east of San Jose. They had to unsnarl over 300 velocity measurements from the various orbiting planets.

The 55 Cancri's system is quite different from that of Earth in some ways. One of its planets circles their sun in under three days, one at 14 days, one at 44 days. The fifth planet takes a whopping 14 years to orbit the star, being a distance of about 539 million miles from it.

Michael Briley, of the National Science Foundation, explains that from the first discovery of a planet circling a star to the discovery of an actual solar system related to a star has taken twelve years, and even that long time is considered an accomplishment of real merit.

Alan Stern, the Science Mission Directorate associate administrator at NASA Headquarters in Washington, finds it significant that we are discovering sytems of a similar complexity to our own.

NASA, Scientists Discover Record Fifth Planet Orbiting Nearby Star