Habitable Zone Planets Could Be Numerous
September 11, 2012

More Habitable Planets Than Previously Thought

Lee Rannals for redOrbit.com - Your Universe Online

Researchers predict that there may be even more planets capable of hosting life out there than previously thought.

Scientists presenting at the British Science Festival in Aberdeen said that new computer models may show there are far more planets that lie in the "habitable zone" than previously estimated.

A new model allows scientists to identify planets that contain underground water which is still in the state of a liquid through planetary heat.

Planets that lie too close to their parent star lose surface water to the atmosphere through evaporation, while those planets lying farther away have water that turns into ice.

A planet must lie a particular distance from its star, or in the habitable zone, in order for it to be capable of hosting life.

The new computer model suggests that planets may be able to keep their water from freezing through heat given off underneath the surface.

Earth's core actually helps to heat up the insides of our planet, and having a similar structure on another planet could keep water that is below the icy surface from turning into a solid.

Moving away from the star takes away the amount of heat the planet receives on its surface, but it doesn't mean liquid water can't exist underneath the surface due to the core of the planet's heat.

"There is a significant habitat for microorganisms below the surface of the Earth, extending down several kilometers," Professor John Parnell, also from Aberdeen University told BBC News. "And some workers believe that the bulk of life on Earth could even reside in this deep biosphere."

The team is developing models to predict which planets might harbor underground reservoirs of liquid water.

"If you take into account the possibility of deep biospheres, then you have a problem reconciling that with the idea of a narrow habitable zone defined only by conditions at the surface,"  Sean McMahon, a PhD student from Aberdeen University, told BBC.

Even planets that are so far from their star, that they receive almost no solar heat, could still maintain underground liquid water, McMahon said. With this taken into account there could be several times more habitable planets.