Pandora. Here is Pandora, a small Saturnian moon. It's orbiting close to the planet as, along with another moon, Prometheus, it's "shepherding" an outer, faint part of Saturn's ring called the "F ring". The rings are seen here edge on under the form of this dark line crossing in front the disk of Saturn. A fine 3-D view of Saturn's cloud tops is seen to the lower left. The small moon is orbiting the gas giant in 15 hours. It's a small celestial body, just 52-mile (84-km) wide. "Shepherding" moons are called this way as their gravitational resonances and tides are shaping -or helping to shape- the rings of Saturn. This picture was taken by the joint NASA/European ESA/Italian Space Agency Cassini mission, which is now performing a 4-year extensive tour of the Saturnian system. Such a comprehensive study will certainly re-write the textbooks, just like the Galileo mission allowed for Jupiter. picture NASA/JPL/Space Science Institute