Saturn Rings Close Up
Saturn is another “Gas Giant” like Jupiter, although not quite as big.
Nevertheless, Saturn is the second largest planet in the Solar System and is huge compared to Earth.
It has a diameter of around 75,000 miles at the equator (less at the poles, due to its rotation) and is over 700 times greater in volume than Earth.
But like Jupiter, it has a lower density than Earth. Saturn would actually float in water!
Saturn’s orbit is twice as far from the Sun as Jupiter, being 887 million miles away, and it takes over 29 Earth years to make one revolution.
Saturn spins quickly on its axis, each Saturn day lasting just 10 hours.
Observing Saturn
Observationally, Saturn is the “wow” object of the Solar System, because of its rings. The rings are easy to see with a modest telescope and must have got many people interested in astronomy. They certainly did it for me!
Saturn’s globe is not nearly so interesting to look at, although it does show some banding, but this is far less marked than that of Jupiter.
The early telescope astronomers, notably Galileo, could not see Saturn’s rings at all clearly. Galileo was confused by what he saw as Saturn’s strange elongated shape.
Saturn’s Rings
Sometimes (about every 13 or 15 years – it alternates), the rings are seen “edge-on” from Earth and almost disappear from our view. This may have been part of Galileo’s problem.
Other times, the rings are seen more “face-on” and it is then possible to see detail in the ring system, including the famous “Cassini Division”, a dark gap between the “A” and “B” rings.
We now know from space probes, that there are actually many thousands of small rings and they are composed of rocks, ice, fine particles and dust.
All this orbiting material is kept in place by the gravitational effects of Saturn’s various satellite moons, including small “shepherd” moons that actually orbit within the ring system.
Space Probes
Visits to Saturn by space probes began with Pioneer in 1979.
Then came the Voyager pair in 1980 and 1981.
These provided close-up images, but the most astonishing images have come recently (2004/5) from the Cassini-Huygens probe. This actually landed on Titan, Saturn’s largest moon.
Saturn’s Moons
Saturn has many satellite moons (over 30) but there are five big ones.
As just mentioned, Titan is the biggest moon and it can be seen with a small telescope. It is actually larger than our Moon, but unlike it, Titan has an atmosphere.
The other largish moons of Saturn (over 600 miles diameter) are Rhea, Iapetus, Dione and Tethys.
Smaller moons of Saturn include Mimas, Enceladus and Hyperion.
