A potentially habitable planet around our closest neighboring star

Exoplanets. This is the name for planets orbiting stars other than our Sun. The possibility of other worlds orbiting the trillions of stars in our universe has been considered by many scientists ever since astronomers realized that our Sun is just one amongst billions of other stars in our universe. However, it was not until the early nineties that scientists were able to observe a planet outside our own solar system. And only recently they discovered one, which has captured their collective imaginations.

Exoplanets are a popular object of astronomy research because they provide astronomers with glimpses into the workings of other star systems and improve our understanding of our own solar system. Because planets are a lot smaller than stars, and since planets do not emit their own light, observing one orbiting a distant star is akin to seeing a bug flying around a stadium floodlight.

Since those first discoveries of exoplanets in the nineties, scientists have designed better ways of discovering these distant worlds, and to date, astronomers have found more than 3.500 of them. But recently, a new potential avenue of space exploration has caught the attention of scientists from all over the world.

Space is big. Unimaginably so. And while most of the exoplanets were discovered around, what we think of as, nearby stars, all of them are still too far away to ever consider visiting, given our current level of technology.

Proxima b

However, in August of 2016, astronomers from the European Southern Observatory (ESO) discovered a planet orbiting our nearest neighbor – Proxima Centauri, which is located “just” 4.25 light-years from Earth. That alone would have been exciting news, but the discovery is even more sensationalistic because the planet, called Proxima b, shares many similarities with Earth. It has roughly the same size as Earth, it is presumed to be rocky (not gaseous like Jupiter), and is located in the “Goldilocks zone” of its star. This means that the temperatures on the planet are suitable for liquid water, a prerequisite for life as we know it. All of these properties, coupled with the planet’s proximity to our solar system, have made this newly found exoplanet the most promising candidate yet for discovering alien life, or perhaps, in hundreds of years, setting up our first colony in interstellar space.

But there are still many things we don’t know about Proxima b, especially ones relating to its habitability. Although Proxima b is of the right size and seems to be in its stars habitable zone, there are numerous factors that could prevent the planet from being habitable. Its parent star, Proxima Centauri, is seven times smaller than our Sun, and much weaker. Even though it is our closest neighbor, it cannot be observed by the naked eye. That means, that for a planet to be warm enough to support life, it also has to be orbiting much closer to its star.

Proxima b is 20 times closer to Proxima Centauri than the Earth is to the Sun, which in turn causes a different problem. As is the case in our solar system with the planet closest to our Sun, Mercury, a planet that is equally close to its star has a great chance of being ‘tidally locked’; that means that the same side of the planet is facing its star at all times, causing a great temperature difference between the two sides of the planet, and might prevent a planet from having an atmosphere.

But even if that is indeed the case, there is still hope. A recent finding by astronomers from Marseille has helped them calculate the possible composition of Proxima b, and there is a big possibility that the planet is covered by an ocean. This large body of water could distribute the temperature on the planet more evenly, and also potentially sustain life.

But another problem for life on Proxima b could be its parent star itself. It is possible that the light it emits oscillates more than the light of our Sun, which might also prevent life from evolving. But scientists simply don’t yet know enough about Proxima b, and its parent star, to have a final answer.

Until astronomers do more research using new and improved methods and instruments, we can only theorize about the potential habitability of the planet orbiting our nearest neighboring star. Whether Proxima b has the potential to support life or not, it’s still a remarkable discovery and, as such, has already been proposed as a target for a future interstellar flyby mission. Who knows, maybe someday a colony of brave humans might call Proxima b their home.

Gaber I.