22 November 2011
This image, acquired by NASA’s Saturn-bound Cassini spacecraft, is a close-up of Saturn’s small geologically-active moon, Enceladus. It shows wonderful terrains on Enceladus’ icy surface. Some of these terrains may be newly formed.
Credit: NASA/JPL-Caltech/Space Science Institute
Saturn has a large family of satellites, consisting of 62 moons and numerous smaller objects, known as moonlets. Saturn’s moons range widely in size, and have various physical and orbital characteristics. NASA recently published an exquisite image of a small intriguing Saturnian moon, known as Enceladus. (Most of the Solar System’s moons have been given names from world’s mythologies.)
The image, acquired by the Saturn-orbiting Cassini spacecraft, is a close-up, showing newly formed terrain in Enceladus’ southern hemisphere. It was taken with Cassini’s narrow-angle camera, on 13 September 2011, when Cassini was approximately 42,000 km away from Enceladus.
Enceladus (504 km across) is an icy moon, whose surface features different types of terrain, including impact craters, plains, cracks and scarps. Intriguingly, Enceladus’ surface is very bright, reflecting most of incident sunlight. For comparison, Earth’s Moon (3,476 km across) reflects only about 6% of light. Enceladus orbits Saturn every 1.4 days (approximately 33 hours), at an average distance of approximately 238,000 km, while the Moon orbits Earth every 27.3 days, at an average distance of about 384,000 km.
This picture shows the relative sizes of Earth (12,756 km across) and Enceladus (504 km across).
The image was generated using NASA images.
Earth image credit: NASA-NSSDC
Enceladus image credit: NASA/JPL-Caltech/Space Science Institute
A Cassini spacecraft image, showing plumes of cold material, emanating from the southern polar region of Enceladus.
Credit: NASA/JPL-Caltech/Space Science Institute
Bizarre Enceladus is geologically active. In 2005, Cassini discovered a rare type of volcanic activity, known as ice volcanoes, on Enceladus. Ice volcanoes occur on very cold objects. They eject cold vapors and ices, unlike Earth’s volcanoes, which spew incinerating lavas. Cassini observed long plumes of ice and vapors, emanating from fractures in the southern polar region of Enceladus. Two other Solar System members are known to have volcanic activity. They are Io (3,642 km across), Jupiter’s spectacular restless moon, and Triton (2,706 km across), Neptune’s largest moon.
References
NASA’s Photojournal
Wikipedia
Further Reading
http://saturn.jpl.nasa.gov
Aymen Mohamed Ibrahem
Senior Astronomy Specialist