Almost 2,000 planets outside of our solar system have been identified, and scientists have come up with criteria for planets that would be considered habitable, including the planet's obliquity - the angle of its axis relative to its orbit around a star, according to Phys.org. Since Earth has a low obliquity, scientists have believed that the more tilt, the less habitable, but that way of thinking might be outdated.
Scientists at MIT believe that even if a planet is sideways like a pig on a spit, the planet could support life - provided there was complete ocean coverage to keep temperatures down. A planet on its side would have daylight for six months followed by darkness for six months because of the tilt toward and away from the sun.
"The expectation was that such a planet would not be habitable: It would basically boil, and freeze, which would be really tough for life," said David Ferreira, a former research scientist in MIT's Department of Earth, Atmospheric and Planetary Sciences (EAPS). "We found that the ocean stores heat during summer and gives it back in winter, so the climate is still pretty mild, even in the heart of the cold polar night. So in the search for habitable exoplanets, we're saying, don't discount high-obliquity ones as unsuitable for life."
"There are one or two terrestrial-sized exoplanets out of a thousand that appear to have densities comparable to water, so the probability of an all-water planet is at least 0.1 percent," said Darren Williams, professor of physics and astronomy at Pennsylvania State University. "The upshot of all this is that exoplanets at high obliquity are not necessarily devoid of life, and are therefore just as interesting and important to the astrobiology community."
The analysis is published in the journal "Icarus."
