The Hubble Space Telescope has discovered bizarre “ghost light,” the remnants of several events billions of years ago where huge galaxies tore each other to shreds, according to a NASA statement.

Six galaxies about the size of the Milky Way were destroyed when gravity combined them over a period of 6 billion years in a region about 4 billion light years away, and Hubble picked up a “faint, ghostly glow” from stars that used to be members of those galaxies. The region is known as “Pandora’s Cluster.”

NASA’s Ignacio Trujillo of The Instituto de Astrofiscica de Canarias in Spain said the data is a step forward in understanding how galaxy clusters evolve.

NASA wrote that the events pulled the galaxies apart “like taffy,” and the ghost light came from stars that had been ripped from their homes, wandering aimlessly through space. By studying these stars, researchers can learn more about the events inside the cluster. However, the discovery matches up with what scientists expected, according to the study’s lead author.

Scientists have been searching for this ghost light for a long time, with 200 billion orphaned stars in the Pandora cluster alone making up 10 percent of its light. It took three years of observations with Hubble to find the ghost light.

Pandora’s cluster includes a total of 500 galaxies.

The results were published in the Astrophysical Journal.