Scientists find 2 planets where life may be more advanced than on Earth
Scientists crack a new mystery behind the Fermi paradox (photo: Frank Cone)
Billions of years don't guarantee a planet will develop complex life — exoplanets may be inhabited only by microorganisms. Scientists have found that the amount of energy available through photosynthesis may be far more important than a planet's age, according to the International Journal of Astrobiology.
Scientists analyzed conditions on 29 nearby exoplanets where liquid water could potentially exist.
Modeling showed that only two of them — GJ 1061c and K2-3d — had a chance for life to evolve beyond the stage reached on Earth. For most of the other worlds, limited light, high temperatures, and insufficient rainfall would be major obstacles.
Photosynthesis as a clock for evolution
Researchers explain that vegetation converts sunlight into chemical energy, creating the foundation needed for complex animal life to emerge.
To assess each planet’s evolutionary potential, scientists compared the amount of carbon fixed throughout Earth’s history with what could be possible on other planets.
Over the 3.2 billion years before vascular plants appeared on Earth, about 2.4 × 10²⁵ grams of carbon was fixed.
The emergence of vascular plants added another 7 × 10²⁵ grams — enabling the emergence of mammals and humans.
On the known planet TRAPPIST-1e, only 21% of the amount accumulated on Earth before the emergence of vascular plants has been fixed over its entire history.
Read also: Fuel from thin air: How astronauts will avoid getting stranded on Mars
Why red dwarfs slow the development of life
Most of the studied worlds orbit dim red dwarfs and are tidally locked, meaning they always face their star with the same side.
As a result, their average annual amount of available light is much lower, while only half of the planet’s surface can receive light suitable for photosynthesis.
Even if such planets are billions of years older than Earth, scientists estimate that life on them could still be stuck at the bacterial stage.
Scientists also point out that a lack of rainfall may be the decisive limitation on plant growth across most potentially habitable exoplanets.
Read also: Did life exist before Earth? Harvard scientists find evidence in meteorites
