If you thought Pan resembled a UFO, Atlas is even more saucer-shaped! Slightly larger at about 19 miles across, Saturn’s moon Atlas was passed by NASA’s Cassini spacecraft on April 12, 2017, coming within about 9,000 miles. The images above are a collection of eight from Cassini’s closest approach. Like its smaller sibling Pan, Atlas has a flattened shape, created by the presence of a large buildup of icy material around its equator.*
Atlas orbits Saturn just outside the edge of the A ring, taking about 14 hours to complete a full orbit.
UPDATE: Here’s a color image of Atlas made from raw images acquired by Cassini on April 12 in infrared, green, and UV wavelengths. I’ve adjusted it to bring out some surface detail and (hopefully) closer match actual visible light.
UPDATE 8-8-18: Here’s another color image of Atlas made from raw images acquired by Cassini on April 12, except this one has been assembled from uncompressed and calibrated raw files so the quality is much better (and hopefully even closer to natural color!) You can find a larger version of it on my Flickr album here.
*This is what the moons Atlas and Pan look like today, but their formations may have been the result of low-angle head-on collisions between small moonlets that resulted in ovoid shapes later pulled flat by Saturn’s gravity. It sounds a little far-fetched, but recent computer models by researchers in Bern seem to indicate that as a likely process. Check out the animation below and read more here.