18 November 2011
Credit: NASA/JPL-Caltech/Space Science Institute
NASA recently published a wonderful picture of Saturn, acquired by the Saturn-orbiting Cassini spacecraft. The image shows a pair of Saturn's icy moons and the planet's graceful rings. Cassini was flying just above the plane of the rings.
In the image, the small geologically-active moon Enceladus (504 km across) shines just below the rings, near the center.
The larger moon, Tethys (1,062 km across), is near the bottom center of the image. (The names Enceladus and Tethys come from Greek mythology. Most of the Solar System’s moons have mythological names.) Tethys is nearer to the Cassini spacecraft than is Enceladus, which was approximately 272,000 km away from Cassini.
Saturn has a large of family of satellites, consisting of 62 moons and numerous smaller objects, known as moonlets. All the Saturnian moons, except for Titan (5,150 km across), Saturn’s largest moon, are smaller than our Moon (3,476 km across).
Saturn’s rings consist of icy particles, ranging in size from dust-sized to boulder-sized objects. The main brighter rings of Saturn are approximately 800,000 km across. However, a gigantic, extremely faint Saturnian ring, approximately 36 million km wide, was discovered in 2009, by a Sun-orbiting NASA spacecraft.
References
NASA’s Photojournal
Wikipedia
Aymen Mohamed Ibrahem
Senior Astronomy Specialist