Distinct days and nights have helped life flourish on Earth. But many alien worlds capable of supporting life may not have such clear delineations. Do

Alien worlds might not have a night and day. How would that change evolution?

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2024-10-13 14:00:07

Distinct days and nights have helped life flourish on Earth. But many alien worlds capable of supporting life may not have such clear delineations.

Do aliens sleep? You may take sleep for granted, but research suggests many planets that could evolve life don't have a day-night cycle. It's hard to imagine, but there are organisms living in Earth's lightless habitats, deep underground or at the bottom of the sea, that give us an idea what alien life without a circadian rhythm may be like.

There are billions of potentially habitable planets in our galaxy. How do we arrive at this number? The Milky Way has between 100 billion and 400 billion stars.

Seventy percent of these are tiny, cool red dwarfs, also known as M-dwarfs. A detailed exoplanet survey published in 2013 estimated that 41% of M-dwarf stars have a planet orbiting in their "Goldilocks" zone, the distance at which the planet has the right temperature to support liquid water.

These planets only have the potential to host liquid water, though. We don't yet know if any of them actually do have water, much less life. Still, that comes to 28.7 billion planets in the Goldilocks zones of M-dwarfs alone. This is not even considering other types of stars like our own yellow Sun.