A total of 60 billion planets capable of supporting alien life may be present just in the Milky Way galaxy alone. That’s the mind-blowing conclusion of a new study by University of Chicago and Northwestern University researchers that was recently published in Astrophysical Journal Letters.
The premise of the new study is that the habitable zone of the planet is the region around a star where it can sustain liquid water.
Too far from a star, and the planet freezes. Too close, and the water boils.
However, a planet’s atmosphere — including its cloud cover — has something to say about that too. As we all know from the current global warming debate, the so-called greenhouse effect occurs when certain atmospheric gasses trap heat, causing a planet to heat up.
In the past searches for habitable zones around extrasolar planets, NASA and other seekers didn’t take into account the effects of cloud behavior.
By simulating how cloud cover stabilizes the weather on planets circling red dwarf stars, the researchers discovered that the habitable zone is much wider than astronomers previously believed.
As a result, a previous NASA estimate of the number of habitable planets in the Milky Way galaxy has been doubled to the stunning total of 60 billion planets capable of supporting alien life.
NASA has estimated that there’s probably only one planet capable of supporting life around each red dwarf in the Milky Way. But the new simulations suggest that each such star could actually host two habitable planets.
In a statement from Northwestern, researcher Nicolas Cowan said:
“Most of the planets in the Milky Way orbit red dwarfs. A thermostat that makes such planets more clement means we don’t have to look as far to find a habitable planet.”
A UC researcher on the project, Dorian Abbot, explained:
“Clouds cause warming, and they cause cooling on Earth. 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.”
They have now proposed a way to use NASA’s James Webb Telescope to detect cloud cover — and liquid water — on alien planets.
And just in case you think 60 billion planets isn’t enough, think about the fact that the Milky Way is just one galaxy.
[alien planet painting by Diverse Pixel via Shutterstock]