A globular cluster of stars known as Palomar 12.

Although it currently resides on the outskirts of the Milky Way’s halo, Palomar 12 was not born here. When astronomers first studied this cluster, they were puzzled by its strangely young age when compared to the other clusters within the galaxy. It appeared to be around 30 percent younger than other Milky Way globulars.

It was revealed that Palomar 12 was actually ripped from its initial home, the Sagittarius Dwarf Elliptical galaxy, around 1.7 billion years ago via tidal interactions between its former home and our galaxy. The dwarf galaxy that Palomar 12 once called home is a satellite galaxy to ours, and closely orbits around us — even occasionally passing through the plane of our galaxy. In fact, it is being slowly torn apart and consumed by the Milky Way.

Credit: ESA/NASA/Hubble Space Telescope