Sat scope discovers Earthlike 'sauna world'

Astronomers using the CoRoT worldfinder satellite say they have discovered the smallest extra-solar planet yet known. The newly-checked-out world is less than twice the size of Earth, may have a solid surface, orbits a sun-like star and appears to have plenty of water. Sadly, local temperatures appear to be more than 1,000°C.

The planet, designated CoRoT-Exo-7b, orbits the star CoRot-Exo-7 more than 450 light years away in the constellation Monoceros. However, it does so in just 20 hours, being much closer to its parent star than Earth - hence the very high temperatures.

According to the European Space Agency, operator of the CoRoT satellite:

Although the density of the planet has not yet been well determined, preliminary indications are that it may be rocky and covered in liquid lava. An alternative proposal is that it may be a "sauna planet" of half water (in a superheated state) and half rock.

To date more than 330 exoplanets have been detected. Most of these are giant, gaseous planets. The discovery of CoRoT-Exo-7b is significant because recent measurements have indicated the existence of small-mass planets but their size has remained undetermined until now.

The CoRoT (COnvection ROtation and planetary Transits) satellite project is led by the Centre National d’Etudes Spatiales (CNES), the French space agency. Its two missions are the search for close-orbiting, smaller planets like CoRoT-Exo-7b and "astroseismology" measurements of stellar oscillations. ®