Saturn's clouds are full of raw beauty, but they also represent a playground for a branch of physics called fluid dynamics, which seeks to understand the motion of gases and liquids. This image is from NASA's Cassini spacecraft.
NASA's Cassini spacecraft looks down at the rings of Saturn from above the planet's nightside. The darkened globe of Saturn is seen here at lower right, along with the shadow it casts across the rings.
NASA's Cassini spacecraft looks toward the brilliant disk of Saturn, surrounded by the icy lanes of its rings. Faint wisps of cloud are visible in the atmosphere. At bottom, ring shadows trace delicate, curving lines across the planet.
This frame from a movie is one of many exposures taken by NASA's Cassnii spacecraft. Cassini stared at Saturn for nearly 44 hours on April 25 to 27, 2016, to obtain exposures showing just over four Saturn days. A movie is available at the Photojournal.
This view captured by NASA's Cassini spacecraft shows Saturn's northern hemisphere in 2016, as that part of the planet nears its northern hemisphere summer solstice in May 2017. Saturn's year is nearly 30 Earth years long.
Saturn's shadow stretched beyond the edge of its rings for many years after NASA's Cassini first arrived at Saturn, casting an ever-lengthening shadow that reached its maximum extent at the planet's 2009 equinox. This image was captured in 2015.
An ethereal, glowing spot appears on Saturn's B ring in this view from NASA's Cassini spacecraft. The glowing effect is an example of an 'opposition surge' making that area on the rings appear extra bright.
NASA's Cassini spacecraft captured this image of Saturn as it views the planet and its expansive rings from all sorts of angles. Here, a half-lit Saturn sits askew as tiny Dione looks on from lower left.
Saturn's moon Tethys appears to float between two sets of rings in this view from NASA's Cassini spacecraft, but it's just a trick of geometry. The rings, which are seen nearly edge-on, are the dark bands above Tethys.
NASA's Cassini spacecraft captured this view of Saturn's moon Atlas (30 kilometers, or 19 miles across), with its smooth equatorial ridge, during a moderately close flyby on Dec. 6, 2015. The view offers one of Cassini's best glimpses of Atlas.
Tethys, dwarfed by the scale of Saturn and its rings, appears as an elegant crescent in this image taken by NASA's Cassini Spacecraft. Views like this are impossible from Earth, where we only see Saturn's moons as (more or less) fully illuminated disks.