New planets outside Milky Way galaxy
It is estimated that there are trillions of planets in the center elliptical galaxy in this image University of Oklahoma

For the first time ever, a group of planets have been discovered beyond the boundaries of the Milky Way galaxy. The alien planets are located in a distant galaxy 3.8 billion light years away and are estimated to have masses ranging from that of the moon to the Jupiter.

The alien worlds were discovered by a team of astrophysicists using data from Nasa's Chandra X-ray space telescope. The researchers used a technique called microlensing, which is an astronomical phenomenon and the only method that is currently capable of detecting planets located at great distances from the Earth.

"We are very excited about this discovery. This is the first time anyone has discovered planets outside our galaxy," Xinyu Dai, a professor of physics and astronomy at the University of Oklahoma, one of the researchers who made the discovery, said in a statement. "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 modeling the data to determine the mass."

Although microlensing has previously been used to hunt for planets in the Milky Way galaxy, the gravitational impact of small space objects can also create signatures, which in turn can be modelled and explained in extragalactic galaxies.

"This is an example of how powerful the techniques of analysis of extragalactic microlensing can be. This galaxy is located 3.8 billion light years away, and there is not the slightest chance of observing these planets directly, not even with the best telescope one can imagine in a science fiction scenario," said Eduardo Guerras, a postdoctoral researcher at the University of Oklahoma, who was also involved in the discovery of the new planets. "However, we are able to study them, unveil their presence and even have an idea of their masses. This is very cool science."

The new research has been published in the Astrophysical Journal Letters.