Astronomers noticed a strange sight in space they had never seen before. A supermassive black hole ejected from the main galaxy, leaving behind a streak of light nearly twice the width of the Milky Way as the shock waves created new stars.

Telescope images often need some cleaning to confirm that what they see exists in space and not just light artifacts like flares, reflections or cosmic ray interference. When astronomers first saw a long line of light in some Hubble Space Telescope images, they assumed it would disappear after applying normal image processing.

However, they were surprised they didn’t, noting that they were actually looking at a line 200,000 light-years long stretching from a galaxy about 7 billion light-years away. Astronomers had never seen this cosmic wonder before, so the team took a closer look to figure out what it was.

And the origin story they found is incredible. A supermassive black hole with the mass of about 20 million suns abruptly blasted out of its galaxy, leaving a bright trail leading back to its former home.

The proof of this story begins at the front end of the line, farthest from the galaxy, where a bright glob of light appears to be coming from ionized oxygen. The team hypothesizes that this is a shock wave in intergalactic gas as the black hole sped through space.

Although we associate black holes with destruction, this hole is actually in a magnificent act of creation. Moving at about 1,600 kilometers (1,000 miles) per second, a black hole is moving too fast to swallow so much matter. Instead, it shocks and compresses the gas, which then cools and merges behind it into brand new stars. So the trail is a thin corridor of child stars that stretches all the way to the galaxy.

So what could cause a supermassive black hole to eject from its parent galaxy? The team says there are only other supermassive black holes. The hypothesis is that the two galaxies merged about 50 million years ago, forming a binary black hole system at the center of this new galaxy. This remained stable for about 10 million years before a third galaxy joined the group with its own supermassive black hole. But, of course, the three crowds and more complex gravitational interactions caused one of the black holes to pop out of the galaxy.

Interestingly, the team says there is some circumstantial evidence for this story. Such a catastrophe would have thrown the other two black holes in opposite directions, and so far there seems to be no sign of an active black hole remaining at the center of the galaxy. A strange feature seen on the far side of the galaxy could be where the other two are currently hiding.

Further observation will be required to confirm the hypothesis or to understand what is actually going on. In the near future, it is planned to study the system with the help of the James Webb Space Telescope and the Chandra X-ray Observatory.