US: Space scientists have announced the discovery of what may be a rocky, earthlike planet orbiting a star 15 light years away - a milestone in the search for a world outside the solar system that could sustain life.
The new planet, dubbed a "super-earth" by the team that found it, is about seven times as big as earth and about twice the diameter. It orbits the star Gliese 876, located in the constellation Aquarius.
Until now every extrasolar planet found has been larger than Uranus, the giant ice planet at the edge of our solar system. Two other planets previously had been found orbiting Gliese 876, a small red star known as an M dwarf, the most common type of star in the galaxy, but these were Jupiter-size gas giants.
The new planet's modest size and mass suggest that it may be the first rocky planet, like earth, that has ever been found orbiting a normal-size star. Researchers think it may resemble the inner planets of this solar system, made of nickel and iron.
"This is a big milestone, to get down to the region of rocky planets," said team member Prof Steven Vogt, of the University of California, Santa Cruz. "We keep pushing the limits of what we can detect, and we're getting closer and closer to finding earths."
Even though the new planet is the closest analogue to earth yet discovered, it could not support life as we know it. Whirling around its star in just two days, it is far too close for water to exist in liquid form. Surface temperatures range from 200 to 400 degrees. "It's not the place to go for a vacation," Vogt said.
That hardly dimmed the excitement of the team, composed of researchers from the University of California, the Carnegie Institution in Washington DC, and the National Aeronautics and Space Administration's Ames Research Centre near Mountain View.
"Today's results are an important step toward answering one of the most profound questions that mankind can ask: Are we alone in the universe?" said Michael Turner of the National Science Foundation, which helped fund the research.
Seventeen other systems also are candidates for a possible earthlike planet. - (LA Times-Washington Post Service)