Astronomers have found signs of a planet in a star system outside of the Milky Way Galaxy. “It’s always fun when you find something that is the first of its kind,” said the study’s lead researcher, Rosanne Di Stefano, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics. “Once we began to find planets locally, it made sense that there were planets in other galaxies, but this is humbling and really exciting.”

If it is confirmed,  this would be the first planet found in another galaxy. According to NBC news, “More than 4,000 exoplanets have been discovered and confirmed, but until now, they have all been in the Milky Way. Most have also been less than 3,000 light-years from Earth.”  The planet was found in a spiral galaxy called Messier 51, which is also known as the Whirlpool Galaxy. The galaxy is more than 23 million light years away from Earth. This planet is thousands of times farther away than any other planet that has been identified.

The planet was found in an X-Ray Binary System. An X-Ray Binary system is typically made up of a normal star and a collapsed star, like a neutron star or black hole. This kind of star system produces and emits X-Rays.

Using data from NASA’s Chandra X-ray Observatory, astronomer Rosanne Di Stefano and her colleagues were able to estimate that the planet was farther from its star than the Earth is to the Sun.  They also were able to estimate that the planet was approximately the size of Saturn, the second largest planet in our solar system.