Artistic depiction of Kepler.
It's hard to believe that the Kepler space observatory has only been in orbit for five years. The plucky spacecraft has discovered hundreds of exoplanet candidates in that short time, even as it's dealt with trying technical challenges. It's also engaged space enthusiasts across the globe with its ever-growing list of discoveries, and has sparked vivacious discussion among experts about the nature of habitable planets in other solar systems.
Kepler has pinpointed many planets in the “Goldilocks zone,” meaning those worlds are close enough to their star to support liquid water, but not so close that the water evaporates into space. Earth is our only dataset when it comes to the development of life, so it makes sense to prioritize these Goldilocks planets as the most likely potential biospheres.
But many scientists want to buck the trend and pan for extraterrestrial life in weirder places. Such is the case with a research team based at the University of Aberdeen (with some help from St. Andrews University). The team published a study in Planetary and Space Science suggesting that subsurface biospheres can survive far beyond the Goldilocks zone.
For the rest of the story: http://motherboard.vice.com/blog/the-habitable-zone-for-exoplanets-may-be-14-times-wider-than-we-thought