Are there any small, Earthlike planets orbiting distant stars? What is it like inside giant and dwarf stars? These two, very different, questions will soon be answered by a unique European space telescope known as COROT.
Expected to launch in December 2006, COROT will become the first spacecraft devoted to the search for planets going around remote stars. Such planets are normally hidden in the glare of their sun and impossible to see. COROT overcomes this problem by looking for a tiny drop in starlight caused by a planet slipping across the face of its parent star.
By studying ‘wobbles’ in distant stars, astronomers have found indirect evidence for more than 200 planets beyond our Solar System. However, nearly all of them are gas giants that dwarf the Earth. COROT promises to find many more of these ‘hot Jupiters’. But some of the planets detected by COROT are expected to be only slightly larger than the Earth.
COROT is most sensitive to small planets with orbits of 50 days or less. That would place them closer to their parent star than Mercury is to the Sun, with temperatures too hot for life to exist – unless the star is a cool red dwarf.
During its two-and-a-half-year mission, COROT will also study changes in light output from thousands of stars. Its special camera will detect tiny variations in brightness caused by starquakes – sound waves rippling across the surface. These will tell scientists what conditions are like inside the star.
