Scientists are now starting to identify potential habitable exoplanets after nearly twenty years of the detection of the first planets around other stars. Over 700 exoplanets have been detected and confirmed with thousands more still waiting further confirmation by missions such as NASA Kepler. Most of these are gas giants, similar to Jupiter and Neptune, but orbiting very dangerously close to their stars. Only a few have the right size and orbit to be considered suitable for any life.
Now the Planetary Habitability Laboratory (PHL) of the University of Puerto Rico at Arecibo (UPR Arecibo) presents a new assessment of the habitability of these worlds as part of its Habitable Exoplanets Catalog (HEC). The catalog not only identifies new potential habitable exoplanets, including exomoons like the Pandora world in the movie Avatar, but also ranks them according to various habitability indices.
The catalog uses new habitability assessments like the Earth Similarity Index (ESI), the Habitable Zones Distance (HZD), the Global Primary Habitability (GPH), classification systems, and comparisons with Earth past and present. It also uses data from other databases, such as the Extrasolar Planets Encyclopaedia (http://www.exoplanet.eu), the Exoplanet Data Explorer (http://www.exoplanets.org), the NASA Kepler Mission (http://www.kepler.nasa.gov), and other sources.
Only two confirmed exoplanets so far match the criteria for habitability in the catalog, Gliese 581d and HD 85512b, both still marginally Earth-like. However, the catalog identifies over 15 exoplanets and 30 exomoons as potential habitable candidates. Future observations with new instruments, such as the proposed NASA Terrestrial Planet Finder (TPF), will be necessary to confirm the suitability for life of any of these candidates.
More Details in the Complete Announcement