GJ 1214b Earth-Like Planet Discovered, Say Scientists

    BEIJING, December 17, 2009, (Xinhuanet) --

Astronomers say they have discovered a water-rich and Earth-like planet in the constellation Ophiuchus.

    The planet, named GJ 1214b, is 2.7 times as large as Earth and orbits a star much smaller and less luminous than our sun in only 38 hours. The size of the star is significant, says David Charbonneau, a Harvard professor of astronomy and lead author of an article on the discovery, which appeared this week in the journal Nature.

    For many years astronomers assumed that planets would only be found orbiting stars that are similar in size to the sun around which the Earth orbits.

    While the newly discovered planet probably has too thick an atmosphere and be too hot to support life similar to that found on Earth, the find is being heralded as a major breakthrough in humanity's search for life on other planets.

    "The big excitement is that we have found a watery world orbiting a very nearby and very small star," Charbonneau said, "Nature is just far more inventive in making planets than we were imagining."

    Instead of using high-powered telescopes attached to satellites, the planet was spotted using an amateur-sized, 16-inch telescope on the ground. There were no technological reasons the discovery couldn't have happened long ago, Charbonneau said. In fact, in astronomical terms it is very close to the Earth at only 40 light years or 378 trillion km (378,000,000,000,000 km).

    The planet orbits a red dwarf, a small and relatively cool star with a surface temperature of less than 3,500 Kelvin (3226.9°C). In comparison the sun around which the Earth orbits is 5,778 Kelvin (5504°C). Its orbital distance also differs significantly with planet GJ 1214b located 2 million km from the red dwarf. The Earth is 140 million km from its sun. At approximately 393–555 K (120–282°C), it may be cooler than any known transiting planet.

    The planetary mass and radius are consistent with the planet being composed prevalently (about 75 percent) of water and about 25 percent rock. It may also be covered by an hydrogen and helium atmosphere making up to 0.05 percent of the mass of the planet according to scientists. Due to the hydrostatic pressure, some of the planet's water could be in the form of ice.

    Planet GJ 1214b has been classified as a "super-Earth" because it is between one and 10 times as large as Earth. Scientists have known about the existence of super-Earths for only a couple of years. Most planets discovered by astronomers have been gassy giants similar to Jupiter or Saturn.

    Charbonneau said it was unlikely that any life on the newly discovered planet would be similar to life on Earth, but he didn't discount the idea entirely. "This planet probably does have liquid water," he said.

    Astronomers have identified around 300 "exoplanets" beyond our own solar system since the first was found some 40 light years from the Sun, just over a decade ago.

    (Agencies)

Editor: Rob Welham