xPsi writes: "Using data from the Sloan Digital Sky Survey, researchers have recently discovered that the galactic halo has two distinct components which rotate in opposite directions. From the article 'The main galactic 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. It orbits in the same direction at about 50,000 mph. The outer halo, a sparsely populated region, spins in the opposite direction at roughly 100,000 mph.' This discovery provides some insight into how galaxies, ours in particular, are formed."