Telescope sees smallest exoplanet
By Paul Rincon
Science reporter, BBC News When planets transit their star, they block out light - like Mercury aboveThe smallest planet yet found outside the Solar System has been detected by a French space telescope.
The rocky world is less than twice the size of Earth.
Only a handful of planets have so far been found with a mass comparable to Earth, Venus, Mars or Mercury.
The discovery was made by Corot, an orbiting observatory with a 27cm-diameter telescope to search for planets orbiting other stars.
About 330 of these "exoplanets" have been discovered so far. But most of them have been gas giants similar to Jupiter or Neptune.
"For the first time, we have unambiguously detected a planet that is 'rocky' in the same sense as our own Earth," said Malcolm Fridlund, Corot project scientist from the European Space Agency (Esa).
"We now have to understand this object further to put it into context, and continue our search for smaller, more Earth-like objects with Corot," he added.
The new find, Corot-Exo-7b, has a diameter less than twice that of Earth and orbits its Sun-like star once every 20 hours.
It orbits very close to its star, and has a high temperature - between 1,000 and 1,500C. This is far too hot for the planet to support life.
The vast majority of exoplanets have been discovered using the radial velocity method.
Full article at: http://news.bbc.co.uk/2/hi/science/nature/7868100.stm