The Milky Way, made up of countless faint stars, can easily be seen in the evening sky this month. Tonight Patrick Moore describes this luminous band which stretches from one horizon to the other, and explains how it forms part of the huge Galaxy of stars in which we live. The latest news will also be given of Mariner 10, the space probe now nearing Mercury, which on 29 March should send back the first close-range pictures of the planet's surface.