Saturn ring
Saturn's rings are made up of billions of particles ranging from grains of sand to mountain-size chunks. Composed predominantly of water-ice, the rings also draw in rocky meteoroids as they travel through space. though Saturn appears surrounded by a single, solid ring when viewed by an amateur astronomer, several divisions exist. The rings are named alphabetically in the order of discovery. Thus the main rings are, from farthest from the planet to closest, A, B and C. A gap 2,920 miles wide (4,700 kilometers), known as the Cassini Division, separates the A and B rings. When Galileo Galilei first observed Saturn in 1610, he thought that the rings were enormous moons, one positioned on each side of the planet. Over several years of observations, he noted that the rings changed shape andeven disappeared, as they changed their inclination with respect to Earth. We now know that Galileo was observing a "ring plane crossing." Saturn's equator is tilted relative to its orbit around the sun by 27 degrees – similar to Earth's 23-degree tilt. As Saturn circles the sun, first one hemisphere and then the other is tilted sunward. The tilt causes seasons, just as it does on Earth, and when Saturn reaches equinox, its equator and ring plane are directly in line with the sun. Sunlight hits the rings edge-on, and the fine line of the rings is difficult to detect. The rings are wide — 170,000 miles across (273,600 km) — but only about 30 feet (10 meters) thick