Sep 25, 2016 I Brett Tingley

First Known Binary Alien Planets Share Curious Connection

The recent discovery of a pair of binary planets has astronomers scratching their heads in wonder. This pair of planets has been so far difficult to classify, as they display characteristics of both brown dwarfs (failed pseudo-stars) and gas giants. So-called binary planets, or pairs of planets that orbit one another around a central point, are a rare phenomenon. It’s much more common for planets to orbit stars, which have much greater masses than other planets.

Binary 01
Binary planets orbit a common point that does not lie within the boundaries of either planet.

According to, the planets are the first of their kind to ever be discovered outside of our solar system. Closer to home, the ex-planet Pluto and its moon Charon are described as a binary system due to the fact that they each orbit a central point that is outside of each other’s boundaries. Each of the two newly discovered planets is thought to be between 200 and 300 million years old, and each has a mass roughly 15 times greater than Jupiter, but still small enough to be classified as planets.

Pluto and her moon Charon are classified as a binary system.

The stars were discovered by Daniella Gagliuffi, a graduate student at the University of California, San Diego. According to Gagliuffi, the close proximity of the objects is unusual, making it likely that their orbits are entwined as a binary system:

They're probably brother and sister. It's a little incestuous. Given that they're so close, it's extremely likely that they're bound.

It’s this proximity to other stars that makes this pair of planets unique; usually, stars have a mass great enough to “lure” planets away from one another and begin orbiting stars. The two planets are found in a dense collection of stars, the closest to them being over ten times farther than Earth is from our Sun. Due to the abundance of nearby stars, it’s difficult to calculate the precise center of orbit for the twin planets.

If confirmed, this finding would make these the first known binary planets outside our solar system.

There is a chance more data collection could reveal that the two planets orbit a distant star together.  There is also chance that one or both of these two planets might be so-called brown dwarfs, which are essentially failed stars and technically not planets. If either of those scenarios turns out to be false, these planets could go down in history as the first known pair of binary exoplanets. Not a bad discovery for a graduate student.

Brett Tingley

Brett Tingley is a writer and musician living in the ancient Appalachian mountains.

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