Proxima b: Our (Potentially) Habitable Neighbor

Artist's impression of the planet orbiting Proxima CentauriOver the last few years, astronomers have discovered thousands of exoplanets, planets that orbit around other stars. Among those thousands, are several dozen planets that are in what we call, the Habitable Zone, a region around a star where there is a possibility that a planet could host liquid water. Of those, fewer still are believed to be similar enough to Earth in mass and radius to be a suitable home for life as we know it, however, early in 2016, astronomers at the European Southern Observatory were able to add another planet to this short VIP (Very Important Planet) list, Proxima b.

Like all exoplanets, Proxima b gets its name from its parent star and a letter designation based on the order it was discovered in that stellar system. The first planet discovered is Star-name b, the next is c, and so on. Most exoplanets that we have discovered so far, orbit stars with majestic names like, HD 209458, Kepler-22, or Pegasi 51. Why does Proxima have a more creative name? Well, like most scientific names, Proxima is a Latin word, it literally translates to “close,” and that is because Proxima is only about 4.2 light-years away, making it the closest star to us other than our Sun. This makes Proxima b the closest exoplanet to us, and potentially the closest habitable planet.

Though Proxima b may be in the right place to have liquid water, there are many other factors that could affect the true habitability of the exoplanet. For example, Proxima is a red dwarf star, meaning that it is much smaller, and much cooler, than our Sun, to compensate for this, Proxima b needs to be much closer to its parent star to get the same amount of heat that we get here on Earth, it is so close, that it takes just over 11 earth days for it to orbit around Proxima. However, just like being closer to a campfire, being closer to a star, even a smaller one comes with some additional dangers: a planet in close proximity to its host star may have to deal with much more high energy radiation, like ultraviolet and x-rays, as well as more powerful solar wind, depleting the atmosphere and killing anything on the surface. Proxima b, may also be tidally locked. This would mean that one one side of the planet, it would always be day, and on the other it would always be night.