Found: First Evidence of Planets Outside the Milky Way

Doug Carpenter
February 7, 2018

Until this study, there has been no evidence of planets in other galaxies.

Astrophysicists have for the first time discovered a population of planets beyond the Milky Way galaxy, using data from NASA's Chandra X-ray Observatory. They think the cluster made up of around 2000 objects like the moon- to Jupiter-sized, per main-sequence star in the galaxy, based on how the galaxy's gravity warped the objects behind it.

Experts say it is still impossible to directly see the newly discovered celestial bodies with even the strongest telescope. This is the first time anyone has discovered planets outside our galaxy.

For the purposes of their study, the researchers relied on the gravitational microlens technique, which relies on the gravitational force of distant objects to focus light from a star.


"These small planets are the best candidate for the signature we observed in this study using the microlensing technique".

Astronomers Xinyu Dai and Eduardo Guerras from the Oklahoma University analyzed a quasar six billion light-years away dubbed as RX J1131-123, which is known as one of the best quasars present in the sky.

Scientists have long thought that exoplanets-planets beyond the solar system-were restricted to the confines of our Milky Way.

A technique called microlensing, which is what the researchers used in this particular effort, uses background light which is bending around an object to study the what lies in between. But they were still able to use their calculations to estimate the number of planets and masses.


There are few methods to determine the existence of distant planets.

This technique was used to detect exoplanets in the Milky Way. But microlensing "can find planets orbiting stars near the center of the galaxy, thousands of light-years away", the society added.

A group of astroboffins from the University of Oklahoma has become the first to demonstrate exoplanet observations in another galaxy - one that's 3.8 billion light years away, or one-third of the distance across the observable universe.

Up until now, while we've been pretty certain that planets must exist in foreign galaxies, we haven't actually be able to spot them-not because they're hiding, but simply because there's a limit to how far our sensors can reach. "If you have only one planet, the chances of observing it twice is astronomically small". As Guerras concisely summarized in the press release, "This is very cool science".


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