The trinary star Alpha Centauri, hangs above the horizon of Saturn

Photojournal: PIA10406

June 18, 2008

The nearest star system, the trinary star Alpha Centauri, hangs above the horizon of Saturn. Both Alpha Centauri A and B -- stars very similar to our own -- are clearly distinguishable in this image. (The third star in the Alpha Centauri system, the red dwarf Proxima Centauri, is not visible here.)

From the orbit of Saturn, light (as well as Cassini's radio signal) takes a little more than an hour travel to Earth. The distance to Alpha Centauri is so great that light from these stars takes more than four years to reach our Solar System. Thus, although Saturn seems a distant frontier, the nearest star is almost 30,000 times farther away.

This image is part of a stellar occultation sequence, during which Cassini watches as a star (or stars) as it passes behind Saturn. Light from the stars is attenuated by the uppermost reaches of Saturn's gaseous envelope, revealing information about the structure and composition of the planet's atmosphere.

The view was captured from about 66 degrees above the ringplane and faces southward on Saturn. Ring shadows mask the planet's northern latitudes at bottom.

The image was taken in visible red light with the Cassini spacecraft narrow-angle camera on May 17, 2008. The view was obtained at a distance of approximately 534,000 kilometers (332,000 miles) from Saturn. Image scale on Saturn is about 3 kilometers (2 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 mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini-Huygens mission visit . The Cassini imaging team homepage is at


NASA/JPL/Space Science Institute