Experts have long known that planets would not be confined to our galaxy, but this is the first time that a celestial body has been discovered outside of the Milky Way.

Researchers from the University of Oklahoma used microlensing – an astronomical phenomenon that allows scientists to use gravity from huge objects such as stars to peer hundreds of billions of lightyears into the universe – to detect the planets.

The scientists say they have detected up to 2,000 planets beyond the Milky Way, in a galaxy around 3.8 billion light years away from Earth and ranging in mass sizes from the moon to Jupiter.

University of Oklahoma researchers used NASA’s Chandra X-ray observatory and were even able to see a quasar – a large celestial object – up to six billion lightyears away.

Xinyu Dai, professor in the Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma College of Arts and Sciences, said: “We are very excited about this discovery. This is the first time anyone has discovered planets outside our galaxy.

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

“We analysed the high frequency of the signature by modelling the data to determine the mass.”

Microlensing, for those who aren’t familiar with the term, is a technique based on gravitational lensing, which happens when light passes near to a super-massive object on its way to us; the massive object can bend the light, focusing it like a titanic telescope lens.

While this is a pretty cool technique, and assuming the detection of these planetary bodies are accurate, then it’s neat but not too surprising.  Our own galaxy is known to be chock-full of planets, so there’s no reason to think that other galaxies would be any different.

No aliens yet, though.  Could our galaxy be like the one in Asimov’s Foundation, Robot and Empire mega-series, where life is common but intelligent life is limited to humanity?  There’s no way to know at the moment; maybe one day we’ll find out.