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 |
| Mass (Earth=1) | 95 |
| Gravity (Earth=1) | 0.92 |
| 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.
