lunes, 13 de junio de 2011

Saturn's Moon Phoebe --Cosmic Mystery with a Violent Past

PIA06426-br500 


Saturn's moon, Phoebe's violent, cratered past is evident in this 3-D image of the tiny moon. The Sun is coming from the left, illuminating craters and bumps on the surface, along with a prominent ridge-like feature in the middle. Bright material, likely to be ice, is exposed atop this ridge-like feature as well as around small craters and down the slopes of large craters. There are also bright streaks on steep slopes, perhaps where loose material slid downhill during the seismic shaking of impact events.


This 3-D mosaic is made up of two images taken with the Cassini spacecraft narrow angle camera on June 11, 2004. 

PIA06401-br500The images left show the moon in ultraviolet. On the right, the image of Phoebe, taken from a distance of 31,000 kilometers (about 19,263 miles) shows an irregular surface and bright crater region (white area). The bright areas indicate water frost on Phoebe's surface. The image was taken by Cassini's ultraviolet imaging spectrograph during the spacecraft's closest approach to Phoebe, on June 11, 2004. The large crater shows clearly in the image on the left.

The colorful graphic below illustrates that despite Phoebe's bumpy, irregular topography, the moon has a fairly round shape. A digitally rendered shape model of Phoebe was constructed using Cassini imaging data obtained before and after the spacecraft's close flyby of the Saturnian moon on June 11, 2004.
The average diameter of Phoebe is about 214 kilometers (133 miles).
PIA06070-br500




Provided by The Daily Galaxy - jpl.nasa.gov