Aliens could be living on moons outside our solar system, scientists have said.
Named "exomoons", the moons orbiting other planets could be a useful clue about where we might find alien life, an astrophysicist has said.
Scientists have found plenty of exoplanets, which orbit stars outside of our solar system. Nearly 4,000 have been found with many more being discovered all the time, and scientists have been shocked by how many of them there are.
But only a limited number of them are actually able to sustain life. Many are either too close or too far away from their sun – meaning that any water, required for life, would either evaporate away or freeze up.
Some of those planets, however, could also have moons. And some of those moons might have the right conditions for liquid water and therefore alien life.
"These moons can be internally heated by the gravitational pull of the planet they orbit, which can lead to them having liquid water well outside the normal narrow habitable zone for planets that we are currently trying to find Earth-like planets in," said Phil Sutton from the University of Lincoln.
"I believe that if we can find them, moons offer a more promising avenue to finding extra-terrestrial life."
Scientists are now trying to find more of those exomoons, in an attempt to understand how well they might serve as a home for life. Doing so is difficult because the moons are so small and distant from Earth.
To overcome that, Dr Sutton used computer simulations to model the rings around an exoplanet known as J1407b. Those rings are 200 times bigger than those around Saturn and researchers looked to see whether the gaps in them were the result of moons.
The research failed to show that the scattered particles around the edge of the ring were not likely to have been caused by another undiscovered moon. But the hunt for more exomoons – and the aliens that could potentially live on them – continues.
