Astronomy and Space
Planets and Moons
Which planets have rings?
Jupiter, Saturn, Uranus, and Neptune all have rings. Jupiter’s rings were discovered by Voyager 1 in March 1979. The rings extend 80,240 miles (129,130 kilometers) from the center of the planet. They are about 4,300 miles (7,000 kilometers) in width and less than 20 miles (30 kilometers) thick. A faint inner ring is believed to extend to the edge of Jupiter’s atmosphere. Saturn has the largest, most spectacular set of rings in the solar system. Saturn’s ring system was first recognized by the Dutch astronomer Christiaan Huygens (1629–1695) in 1659. Its rings are 169,800 miles (273,200 kilometers) in diameter, but less than 10 miles (16 kilometers) thick. There are six different rings, the largest of which appears to be divided into thousands of ringlets. The rings appear to be composed of pieces of water ice ranging in size from tiny grains to blocks several tens of yards in diameter.
In 1977 when Uranus occulted (passed in front of) a star, scientists observed that the light from the star flickered or winked several times before the planet itself covered the star. The same flickering occurred in reverse order after the occultation. The reason for this was determined to be a ring around Uranus. Nine rings were initially identified, and Voyager 2 observed two more in 1986. The rings are thin, narrow, and very dark.
Voyager 2 also discovered a series of at least four rings around Neptune in 1989. Some of the rings appear to have arcs, areas where there is a higher density of material than at other parts of the ring.