12 May 2009
Saturn’s moon Dione
Credit: NASA/JPL/Space Science Institute
NASA recently published a stunning image of a Saturnian moon, acquired by the Saturn-bound Cassini spacecraft. The moon, known as Dione (1,120 km across), is visible as a slender crescent, as the spacecraft and the Sun were nearly on opposite sides of it. The outline of a crater is just visible in Dione’s southern hemisphere.
The image was taken in visual light, with Cassini’s narrow-angle camera, on 25 February 2009. The spacecraft was approximately 484,000 km from Dione. Image scale is 3 km per pixel.
Dione is the second densest of Saturn’s numerous moons. It is believed to be composed predominantly of ice, with a significant proportion of rocks. Like our Moon (3,476 km across), Dione rotates synchronously, i.e., it keeps the same side turned to its parent planet. Dione orbits Saturn every 2.7 days, at an average distance of approximately 380,000 km. In Greek mythology, Dione was the mother of Aphrodite (Venus).
Further Reading
The Cassini Mission Homepage
http://saturn.jpl.nasa.gov/
Aymen Mohamed Ibrahem
Senior Astronomy Specialist