A system of shining rings makes Saturn a very distinctive planet. We see the rings from different angles at different times as the planet circles the Sun every 30 years. Second in size only to Jupiter, Saturn is also made up mainly of gas. It is the lightest (least dense) planet, and would float if placed in water. Like Jupiter, Saturn has bands of clouds in a deep atmosphere, but they are much fainter than Jupiter’s.
Table 15. ESSENTIAL DATA
|Diameter at equator||120,536 km (74,900 miles)|
|Average distance from Sun||1,427 million km (88,672 million miles)|
|Orbital period||29.46 years|
|Rotation period||10.66 hours|
|Cloud-top temperature||-140°C (-220°F)|
|Number of moons||30|
From Earth, just three rings – A, B, and C – can be seen around Saturn. They span a total distance of about 275,000 km (170,000 miles). Space probes have discovered several other rings both inside the C ring and further out beyond the A ring.
Saturn’s rings are made up of chunks of ice and dust whizzing round the planet at high speed. They vary in size from particles as small as sand grains to huge boulders. No one is sure where this material came from. It could be the remains of ancient moons or maybe the debris of comets that came too close.