Scientists launch 'planet hunter'


December 27, 2006

COROT will measure the light emitted by a star and detect the drop in brightness caused when a planet passes in front of it

PARIS, France (Reuters) -- A French-led satellite launched on Wednesday to seek out new Earth-like planets beyond the solar system and to explore the interior of stars.

The COROT project sent into orbit a telescope capable of detecting planets smaller than is currently known -- some maybe just a few times the size of Earth and rocky, rather than the larger, gaseous types, the European Space Agency (ESA) said.

"COROT will be able to find extra-solar planets of all sizes and natures, contrary to what we can do from the ground at the moment," Claude Catala, one of the researchers associated with the project, told France Info radio.

"We expect to obtain a better vision of planet systems beyond the solar system, about the distribution of planet sizes," she said. "And finally, it will allow us to estimate the likelihood of there existing planets resembling the Earth in the neighborhood of the sun or further away in the galaxy."

COROT launched at 1423 GMT from Kazakhstan.

Planets have been found orbiting stars other than the sun but they have never been seen. Instead, scientists have deduced they are there based on the stars' "wobble", the result of the gravitational pull of planets revolving around them.

COROT, a project of the French National Space Studies Center (CNES) in which ESA is participating, will be able to detect smaller, rocky planets by using a different method.

It will measure the light emitted by a star and detect the drop in brightness caused when a planet passes in front of it.

Like the larger planets found so far, however, these new ones will have to be orbiting close to their star.

"Such planets would represent a new, as yet undiscovered, class of world that astronomers believe exists. With COROT, astronomers expect to find between 10-40 of them, together with tens of new gas giants," ESA said.

ESA said COROT would also be used to track sound waves that resonate through a star, creating changes in brightness that should give scientists a glimpse into the interior of the stars themselves.

"These create a 'starquake' that sends ripples across the star's surface, altering its brightness. The exact nature of the ripples allows astronomers to calculate the star's precise mass, age and chemical composition," it said.

In 2008, the U.S. National Aeronautics and Space Administration (NASA) is due to launch the first space telescope capable of detecting Earth-sized planets in similar orbits to ours, ESA said.