Proxima B is the Closest Planet to Our Solar System and It Might Be Habitable

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The planet’s mass suggests Proxima b is rocky. Artist impression: ESO/M.KORNMESSER
The planet’s mass suggests Proxima b is rocky. Artist impression: ESO/M.KORNMESSER

Proxima b is a planet, roughly 1.3 times the size of Earth and which is located in orbit around the closest star to our own solar system, Proxima Centauri. The location in relation to its parent star may suggest that Proxima b is actually a rocky planet and not a tiny gas giant.

“It’s not only the closest terrestrial planet found, it’s probably the closest planet outside our solar system that will ever be found because there’s no star closer to our solar system than this one,” Ansgar Reiners, an astrophysicist at Gottingen Institute for Astrophysics and co-author on the paper

Reiners and his colleagues have observed Proxima b circling its star on a stable orbit every 11.2 days. Now, the thing is that they don’t know if it has an atmosphere. If it does, then average temperatures would be between minus 30 and plus 30 degrees Celsius. If there is no atmosphere to speak of then temperatures would be at about minus 40 degrees. And since the planet orbits so close to the star, it has a radiation exposure 100 times greater than what we see here on Earth. This is what the researchers have reported in the journal Nature.

This close proximity to the star could mean that all water on the surface would be boiled off instantly. But not necessarily. If Proxima b formed further away from the star, it could have come in contact with ice comets which would have brought with them enough water. Moreover, if there is indeed an atmosphere to begin with, then the water could still be there. What’s more, it seems that Proxima b is tidally locked to the star it orbits around. This means that only one side of the planet is facing the star; just like the moon is in relation to the Earth.

One side is always sunny, the other is gloomy and dark,” Guillem Anglada-Escudé, a researcher at Queen Mary University of London and lead author on the new paper, said during a recent briefing.

“This planet is at 5% of the Earth’s distance from the Sun. However, Proxima is 1,000 times fainter than the Sun. So the flux – the energy – reaching Proxima b is about 70% of what the Earth receives. It’s like taking Earth a bit further away, but it’s comparable,” explained Dr Anglada-Escudé to the BBC.

Now, whether Proxima b has water or not, whether it has an atmosphere or not, are a matter of debate and can’t be confirmed from here on Earth right now. Being some only 40 trillion kilometres away, we could theoretically send a spacecraft over there and actually take a closer look.

Russian billionaire Yuri Milner has said last year that he is willing to invest some $100 million in a program designed to fly to Proxima Centauri. The project is called Breakthrough Starshot wich involves sending a tiny craft powered by lasers. But there may be problems with this program as shown by a recent study made by Harvard University, where it sais that tiny dust particles can pose a serious threat to the tiny craft.