The Habitable Exoplanets Catalog is a database of the planets outside our solar system which are considered the most suitable for life according to certain steps and metrics. So far 16 have been identified as possible candidates. This Guardian article is a good introduction. You can also just dive into the catalogue, which ranks planets on two main scales, similarity to Earth and surface habitability (note that all images are computer renderings). The catalog is a project of the Planetary Habitability Laboratory at University of Puerto Rico in Arecibo (home to the world’s largest radiotelescope).
meanwhile.. The BBC does it this way: It is the closest confirmed planet yet to one like ours – an “Earth 2.0″. No confirmation yet if it is rocky, watery, or gaseous.
but… NASA puts it this way: NASA’s Kepler Mission Confirms Its First Planet in Habitable Zone of Sun-like Star.
Closer to Finding an Earth
This artist’s conception illustrates Kepler-22b, a planet known to comfortably circle in the habitable zone of a sun-like star. It is the first planet that NASA’s Kepler mission has confirmed to orbit in a star’s habitable zone — the region around a star where liquid water, a requirement for life on Earth, could persist. The planet is 2.4 times the size of Earth, making it the smallest yet found to orbit in the middle of the habitable zone of a star like our sun.
Scientists do not yet know if the planet has a predominantly rocky, gaseous or liquid composition. It’s possible that the world would have clouds in its atmosphere, as depicted here in the artist’s interpretation.
Image credit: NASA/Ames/JPL-Caltech