A dark halo of gas that envelopes our neighboring Andromeda galaxy is 1,000 times more massive than previously measured and stretches halfway to the Milky Way.
Mysterious Spot 5 - most prominent of Ceres' bright spots - is shown to consist of many smaller spots in a new image from the orbiting Dawn spacecraft.
Tiny debris particles cause wear and tear on active satellites. A team wants to find it and zap it with a laser to cause its fall back into Earth's atmosphere.