Aliens could be common on free-floating ‘rogue planets’ without suns, scientist says

‘Rogue planets’, which orbit galaxies without a parent sun, could harbour life beneath their surface, a scientist claims - and extraterrestrial lifeforms could be more common than we have thought.

The ‘free floating’ planets, not bound to any star, are common in our galaxy - with one study suggesting that there are 100,000 times as many ‘rogue’ planets in the Milky Way than the galaxy’s 300 billion stars.

“You don't necessarily need a sun for the maintenance of life. Life can survive on a rogue planet if it is far enough below the surface and the planet is generating enough heat,” says Sean McMahon of the University of Aberdeen.

“Life doesn't need oxygen gas, sunlight or organic food. It can survive at high temperatures and pressures, miles below the Earth's surface, feeding off chemical reactions between water, minerals and carbon dioxide. That's probably a common environment elsewhere.”