Top Ten Mysteries of the Universe

From Smithsonian:

1. What Are Fermi Bubbles?

No, this is not a rare digestive disorder. The bubbles are massive, mysterious structures that emanate from the Milky Ways center and extend roughly 20,000 light-years above and below the galactic plane. The strange phenomenon, first discovered in 2010, is made up of super-high-energy gamma-ray and X-ray emissions, invisible to the naked eye. Scientists have hypothesized that the gamma rays might be shock waves from stars being consumed by the massive black hole at the center of the galaxy.

2. Rectangular Galaxy

“Look, up in the sky! It’s a…rectangle?” Earlier this year, astronomers spotted a celestial body, roughly 70 million light-years away, with an appearance that is unique in the visible universe: The galaxy LEDA 074886 is shaped more or less like a rectangle. While most galaxies are shaped like discs, three-dimensional ellipses or irregular blobs, this one seems to have a regular rectangle or diamond-shaped appearance. Some have speculated that the shape results from the collision of two spiral-shaped galaxies, but no one knows for now.

More here.