NASA picks up mysterious signal from outside our galaxy

Space enthusiasts and X-Files fans, get ready, because NASA astronomers have found an unexplained "signal" coming from outside our galaxy.

Scientists were looking at more than a decades-worth of data from one of NASA's main telescopes when they picked up the signal.

It was "an unexpected and as yet unexplained feature outside of our galaxy," wrote Francis Reddy of NASA's Goddard Space Flight Center.

The powerful Fermi Gamma-ray Space Telescope orbits the Earth 24/7, looking for gamma rays – bursts of light which are many times more powerful than what our eyes can see.

Gamma rays are often created when a star explodes or a nuclear blast happens. Safe to say, they're pretty dramatic things.

The scientists had been looking for the oldest signs of gamma rays in the universe, which may have had a part in creating the first atoms. These signs are known as cosmic microwave background, or CMB.

This background tends to have a so-called dipole structure which means one end is hotter, and carries more energy, than the other. Scientists think the motion of our solar system creates this structure, or direction.

Instead, the researchers found a signal coming from a similar direction, but which had some of the most energetic particles they had ever found.

"We found a gamma-ray dipole, but its peak is located in the southern sky, far from the CMB's, and its magnitude is 10 times greater than what we would expect from our motion," said Chris Shrader, an astrophysicist at Goddard.

A paper describing the findings was recently published in The Astrophysical Journal Letters.

The scientists think the signal is related to a similar discovery made by Argentinian scientists in 2017, and that the two could come from a single, unidentified source.

Alexander Kashlinsky, a cosmologist at the University of Maryland and NASA's Goddard Space Flight Center, said: "It is a completely serendipitous discovery. We found a much stronger signal, and in a different part of the sky than the one we were looking for."

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