Researchers from the University of Aberdeen and University of St. Andrews said these planets had been considered uninhabitable, but they now believe such planets can support life below the surface.
The team created a computer model that estimated subsurface temperatures given the planet's distance from its star.
"A planet needs to be not too close to its sun but also not too far away for liquid water to persist, rather than boiling or freezing, on the surface," said PhD student Sean McMahon.
The researchers found that by including the the top five kilometers below the surface they could increase the habitable zone for an Earth-like planet by three times. On Earth, life has been found as deep as 5.3 kilometers and could exist as deep as 10 kilometers.
“The model shows that liquid water, and as such life, could survive 5km below the Earth's surface even if the Earth was three times further away from the sun than it is just now," said McMahon.
The current habitable region for the Earth extends to Mars but this model suggest that it could extend out to Jupiter or Saturn. This also means that many so-called rogue planets drifting far from stars in near darkness could actually be habitable.
[University of Aberdeen]