The two giant bubbles of high-energy gamma rays protruding from the Milky Way, each spanning 25,000 light-years across, roughly the size of the galaxy itself. According to NASA, the bubbles are emitting about the same amount of energy as 100,000 exploding stars, or supernovae.

The bulbous features may be evidence of a burst of star formation a few million years ago, researchers said. Or they may have been produced when a super-massive black hole eruption in the center of our galaxy that gobbled up a bunch of gas and dust.