What causes small waves in Saturn's rings? Observations of rings bordering the Keeler gap in Saturn's rings showed unusual waves. Such waves were first noticed last July and are shown above in clear detail.

In 1930, tiny, icy world Pluto was discovered orbiting in the distant solar system. In 1978, its relatively large companion Charon was detected by ground-based observations. This year, the Hubble Space Telescope may well have detected two further members of the Pluto system.

Why is Umbriel so dark? This dark moon reflects only half the light of other Uranus' moons such as Ariel. And what is that bright ring at the top? Unfortunately, nobody yet knows. These questions presented themselves when Voyager 2 passed this satellite of Uranus in January 1986.