Science How can astronomers tell the difference between a group or cluster of stars and an actual galaxy?
Science Could the huge gamma-ray bubbles that extend above and below the center of the Milky Way be a boundary of matter and antimatter, whose collision emits gamma rays?
Science If the Andromeda and Milky Way galaxies collide head-on when the two are predicted to merge five billion years from now, what is likely to happen to the Large and Small Magellanic Clouds?
