Space. It’s an expansive cold place full of giant scary
things–huge terrifying object like these space bubbles. There are two of them,
jutting out on either side of the Milky Galaxy, north and south. The two
objects, taken together, measure 50,000 light years.

The giant space bubbles weren’t discovered until recently,
when astronomer Doug Finkbeiner happened upon them at the Harvard-Smithsonian
Center for Astrophysics in Cambridge,
Massachusetts, thanks to NASA’s Fermi
Gamma-Ray Telescope.

So, what are they? Who knows? Not  Finkbeiner. He told the press, "We don't fully
understand their nature or origin." We do know that they're big, however–they take
up roughly half of the visible sky. Apparently we've haven't seen them until
now, thanks to all of the gamma radiation in the sky.