Icy, impact-riddled Mimas (396 kilometers, 246 miles across) slips briefly in front of the moon Janus (179 kilometers, 111 miles across) in this movie from Cassini.
The movie was created from 37 original images taken over the course of 20 minutes as the spacecraft’s narrow angle camera remained pointed toward Janus. Although Mimas moves a greater distance across the field of view, Janus also moved perceptibly during this time. The images were aligned to keep Janus close to the center of the scene. Additional frames were inserted between the 37 Cassini images in order to smooth the appearance of Mimas’ movement – a scheme called interpolation. Close-up images from the few minutes surrounding the occultation are arranged into a strip along the bottom of the movie.
The terrain on Mimas seen here is about 80 degrees to the west of that visible in a previously released movie (see PIA06198), which showed the little moon appearing to cross Saturn’s ring plane from Cassini’s vantage point. In that previous movie, the rim of the large impact crater Herschel (130 kilometers, 80 miles wide) was visible as a flattening of the moon’s eastern limb. In the new movie, Herschel is almost at dead center.
Contrast on Janus was mildly enhanced to aid the visibility of its surface. The right side of Mimas appears bright because the moon was partly overexposed in this image sequence.
The images for this movie were taken in visible light on March 5, 2005, when Cassini was approximately 1.8 million kilometers (1.1 million miles) from Mimas and 1.9 million kilometers (1.2 million miles) from Janus. The image scale is approximately 11 kilometers (7 miles) per pixel.
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Science Mission Directorate, Washington, D.C. The imaging team consists of scientists from the US, England, France, and Germany. The imaging operations center and team lead (Dr. C. Porco) are based at the Space Science Institute in Boulder, Colo.