Investigating exoplanet surfaces

In order to better understand the composition of rocky exoplanets, researchers have proposed a method to identify chemical signatures from surface materials. A better understanding of exoplanet surface compositions will help researchers determine the prevalence of Earth-like planets in our galaxy.

Numerous rocky, Earth-like worlds have been discovered by transit surveys such as the Kepler mission. For those familiar with the transit of Venus last year, exoplanet transits are the same idea - an exoplanet crosses the face of its parent star as perceived by observers on Earth. By comparing the amount of starlight the transiting planet blocks and the total starlight emitted by the host star, astronomers can determine the radius of a transiting planet.

Recent surveys have hinted at the existence of exoplanets with rocky surfaces, making them similar to our own "terrestrial" planets Mercury, Venus, Earth and Mars. However, a number of the exoplanets thought to have rocky surfaces appear to not have any significant atmospheres. One such exoplanet is Corot-7b, which orbits very close to its parent star. Exoplanet 55 Cancri e, estimated to have roughly twice Earth's radius and roughly eight times Earth's mass, also may be a rocky planet, and perhaps even made of diamond.