New planet
A team of European astronomers said that the most enticing property yet found outside our solar system is about 20 light-years away in the constellation Libra. They have discovered a planet five times as massive as the earth orbiting a dim, red star known as Gliese 581.
Dr.Stephane Udry of the Geneva Observatory said that it orbits its home star within the so-called habitable zone where surface water, the staff of life, could exist if other conditions are right. He said that they were at the right place for that. He and other astronomers cautioned that it was far too soon to conclude that liquid water was there without more observations.
Sara Seager, a planet expert at the Massachusetts Institute of Technology, said if the planet had an atmosphere more massive than Venus’s, then the surface would likely be too hot for liquid water. The discovery in the Gliese 581 system, where a Neptune-size planet was discovered two years ago is now suspected, catapults that system to the top of the list for future generation of space missions.
Dr.Dimitar Sasselov of the Harvard-Smithsomian Centre for Astrophysics, who studies the structure and formation of planets, said that we can go there becauese it is 20 light-years.
An advanced spectrograph on a 141-inch-diameter telescope was used by Udry’s team at the European observatory in La Silla, Chile. The planet, Gliese 581, circles the star every 13 days at a distance of about seven million miles. According to models of planet formation developed by Sasselov and his collegues, such a planet should be about half again as large as the earth and composed of rock and water.
Although the new planet is much closer to its star than Earth is to the Sun, the red dwarf Gliese 581 is only about a hundredth as luminous as the Sun. So seven million miles is a comfortable hoding distance. Using the earth and Venus as two extreme examples, Udry estimated that temperatures on the surface of the planet should be in the range of 0 degree to 40 degree centigrade.
