They located not too close to their star, therefore not too hot, and not too far from their stars, therefore able to support liquid water.
According to a statement released by NASA, this discovery brings the total number of identified planets to 4,034, 2,335 of which have been verified as exoplanets – planets outside our solar system. 50 of these are in habitable zones, and more than 30 have been verified.
The statement said, “There are now 4,034 planet candidates identified by Kepler. Of which, 2,335 have been verified as exoplanets. Of roughly 50 near-Earth size habitable zone candidates detected by Kepler, more than 30 have been verified.
“Additionally, results using Kepler data suggest two distinct size groupings of small planets. Both results have significant implications for the search for life.”