Though only about dozen potentially habitable exoplanets have been detected so far, scientists say the universe should be teeming with alien worlds that could support life. The Milky Way alone may host 60 billion such planets around faint red dwarf stars, a new estimate suggests.
Based on data from NASA’s planet-hunting Kepler spacecraft, scientists have predicted that there should be one Earth-size planet in the habitable zone of each red dwarf, the most common type of star. But a group of researchers has now doubled that estimate after considering how cloud cover might help an alien planet support life.
“Clouds cause warming, and they cause cooling on Earth,” study researcher Dorian Abbot, an assistant professor in geophysical sciences at the University of Chicago, said in a statement. “They reflect sunlight to cool things off, and they absorb infrared radiation from the surface to make a greenhouse effect. That’s part of what keeps the planet warm enough to sustain life.”
The habitable zone is defined as the region where a planet has the right temperature to keep liquid water on its surface, thought to be a requirement for life as we know it. If a planet is too far from its star, its water freezes; too close, water vaporizes. Since red dwarfs are dimmer and cooler than our sun, their habitable zone is much cozier than our solar system’s.
“If you’re orbiting around a low-mass or dwarf star, you have to orbit about once a month, once every two months to receive the same amount of sunlight that we receive from the sun,” explained another study author, Nicolas Cowan, a postdoctoral fellow at Northwestern University.
Join our list
Subscribe to our mailing list and get interesting stuff and updates to your email inbox.
More from Space Exploration
Uranus smells like farts, astronomers have confirmed — and the discovery indicates there was ‘a big shakeup’ early in the solar system
A photo of Uranus taken by Voyager 2 in 1986 (edited to show its moon and rings).NASA/JPL-Caltech Uranus is one of the …
Indian Prime Minister Narendra Modi has claimed his forces shot down a low-earth satellite in a pre-planned test. Such capabilities …