Proxima b: A New World

by Patricia Paje


On August 24, 2016, scientists announced the detection of an exoplanet orbiting Alpha Proxima (or more commonly known as Proxima Centauri), the nearest star to our own sun.

An exoplanet is any planet orbiting a star other than our own. The planet was named Proxima Centauri b after its star. Not only is this planet special because it is orbiting the closest star to us (and by close we mean 4.22 light-years or 25 trillion miles away), but the exoplanet is found to be in the star’s habitable zone.

The habitable zone is a range of planetary orbits around a star in which the planet has the right conditions to support life. A star’s habitable zone is based upon the mass of the star and a planet’s distance from the star.

Proxima b was indirectly detected by astronomers at Queen Mary University in London by observing 16 years of data by two telescopes in Chile. Through the data, the astronomers were able to conclude that Proxima Centauri had incredibly tiny amounts of motion which was due to Proxima b’s orbit.

Astronomers have not seen Proxima b directly, but have concluded some notable features of the most exciting exoplanet to be discovered.

Proxima b is roughly 1.3 times as massive as Earth, making astronomers conclude it is a rocky planet. Depending on the atmospheric conditions of Proxima b, it may be the right temperature to have liquid water, thus host life. Its orbit takes just about 11 Earth days to complete leading astronomers to believe that Proxima b has no seasons and potentially be tidally locked (meaning only one side of the planet faces the sun similar to how we only see one side of the moon from Earth). Having a tidally locked planet means that there is a possibility that liquid water only exists on the sun facing side, but astronomers are hopeful that atmospheric winds could transport heat around the planet. In addition, astronomers are weary that Proxima b is close enough to its sun (although still in its habitable zone) that it becomes pelted with radiation from solar flares.

Although Proxima b has not been directly detected, it is close enough to Earth that future telescopes like the James Webb launching in 2018 should be able to directly image the exoplanet.

Proxima b could be the target of many future interstellar missions. The age old question, are we alone, might finally be answered.