Astronomers take a look at the history of the Milky Way. While it’s relatively peaceful now, it formed by pulling in several smaller galaxies and ripping them to pieces.

via National Air and Space Museum

Most of those galaxies are long gone (there’s one survivor, but it, too, is doomed). Yet hints of the merged galaxies remain. And like archaeologists, astronomers are digging through the remains to help piece together the history of the Milky Way. They’re learning how the galaxy grew, how its wide disk changed over the eons, and how it’s being influenced by other galaxies even now.

“Galactic archaeology is looking at the fossil record of our galaxy,” says Melissa Ness, an astronomer at Columbia University and the Center for Computational Astrophysics at the Simons Foundation. “We’re winding back the clock to understand what it looked like one billion years ago, two billion years ago, and so on, back to the earliest times.”

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