Potentially habitable Earth size planet forty light years away

4 July 2024

That’s the good news. Tory Shepherd, writing for The Guardian, says the recently discovered exoplanet, dubbed Gliese 12b, might be able to host liquid water. We all know what that means. If there’s water, there may be life. Gliese 12b is so named because it orbits a star called Gliese. Now for the bad news. Gliese is a red dwarf.

I personally don’t have a problem with red dwarf, or M-type, stars. They’re actually kind of cool. And common. Up to seventy-five percent of stars in the cosmos are thought to be red dwarfs. The star nearest to Earth, Proxima Centauri, is a red dwarf. And while most stars in the universe have relatively short lifespans — for instance the Sun, which is about half way through its ten billion year life — red dwarfs live for trillions of years.

The last stars — as we currently understand them, at least — shining in the universe, will be red dwarfs. Go the red dwarfs. But, the problem is any planets orbiting in a red dwarf’s habitable-zone, will be tidally locked. That is, only one side of the planet will face its host star. That half of the planet therefore, in this case Gliese 12b, will be overly warm, while the other, dark side, will be rather cold.

This may not be particularly conducive to life. But some scientists have suggested life on planets orbiting red dwarfs in the habitable-zone, may take hold near the day-night terminator. This is where it will be neither too hot, nor too cold. But this would be an extremely narrow corridor, somewhat limiting the chances of life, especially intelligent life, developing.

Then there’s the red dwarfs themselves. They’re prone to regularly emitting intense radiation flares, which could have the effect of sterilising the surface of nearby planets. This points to the likelihood of Gliese 12b not being all that habitable at all. I think we need to reserve our excitement for the discovery of habitable Earth size planets, for maybe when they’re found orbiting other types of stars.