NASA scientist Tom Barclay says new discoveries by the Kepler satellite mean habitable planets are no longer just "theoretical":
T. Barclay: These discoveries suggest that there are many habitable, small planets.
T. Barclay: Discussing habitable planets is no longer a theoretical exercise.
More top news
NASA's Juno spacecraft has skimmed the clouds above Jupiter in a record-breaking close approach to the planet.
Sunny spells and scattered showers this Sunday
A fresh round of singing hopefuls put aside their nerves to face the X Factor judges as the talent show returns for a new series.