“We still have a lot to understand.”
Masashi Chiba of Japan’s Tohoku University.
If gazing up at the Milky Way can make you feel dizzy, it could be because the outer galaxy has been discovered to be a mix of two distinct components rotating in opposite directions. The Milky Way’s main disk, home to our sun, rotates at an average speed of 500,000 mph. Surrounding the disk is what’s now called the inner halo, which orbits in the same direction at about 50,000 mph. The thinly populated region, outer halo, spins in the opposite direction at roughly 100,000 mph.