Credit: NASA/JPL/Space science Institute

 

NASA recently published a fascinating movie, acquired by the Saturn-bound Cassini spacecraft. The movie shows Saturn's geologically active moon, Enceladus, transiting Rhea, Saturn's second largest moon.

 

Play Movie

http://www.nasa.gov/mov/166433main_pia08350-movie.mov

 

The moons appear as bright crescents, due to Cassini's position with respect to the Sun and the moons. When Enceladus (505 km across) approaches Rhea (1,528 km across), the shadow of Saturn is projected onto the unlit side of its magnificent rings.

 

The movie was produced using 40 images taken with Cassini's narrow angle camera, over a period of about 20 minutes. Additional frames were inserted to smooth the motion of the moons, a technique known as interpolation.

 

The images were taken in visible light, on 2 March 2006, at a distance of approximately 2.8 million km from Rhea, and 2 million km from Enceladus. Image scale is 17 km per pixel on Rhea, and 12 km per pixel on Enceladus.

 

Reflecting over 90% of incident sunlight, Enceladus is the most reflective object in the Solar System. Due to this high reflectivity, Enceladus has a very cold surface.

 

Rhea's surface is densely cratered with bright wispy markings. Cassini is scheduled to fly by Rhea on 30 August 2007, at a distance of approximately 5,000 km.

 

Further reading

Cassini-Huygens Mission

http://saturn.jpl.nasa.gov/home/index.cfm

 

 

Aymen Mohamed Ibrahem