Habitable or Not?

Our closest planetary neighbor remains in good view early this month. Venus is the “evening star,” shining from about 32 million miles away. Despite its beauty, though, it’s not a friendly place to visit. Its surface is extremely hot, and it has a dense, toxic atmosphere.

The closest planet beyond our solar system could be similar to Venus. Then again, it could be similar to our own Earth.

Proxima Centauri b orbits our closest neighboring star, Proxima Centauri, which is four and a quarter light-years away. The planet is probably dense and rocky, like Earth and Venus. And it lies inside the star’s habitable zone — the distance from the star where temperatures are just right for liquid water.

That doesn’t mean the planet is actually habitable, though. A lot depends on what happened when it was young.

Proxima Centauri is small, cool, and faint. When the star was born, though, it was much hotter and brighter than it is now. That means a lot could have happened to the young planet.

Researchers looked at many possible early conditions for it — with a thick atmosphere and lots of water on its surface, for example. They found that the young star could have vaporized both of them, leaving the planet dry and airless, or with a Venus-like atmosphere. But many scenarios led to conditions that were more like Earth.

We won’t know what Proxima Centauri b is really like until future telescopes allow us to get a direct look at this neighboring world.

Script by Damond Benningfield