Based on images from the NASA Cassini spacecraft, astronomers have found that Pan and Atlas, two moonlets of Saturn, have huge flat ridges around their middles (at their equators). The moonlets, or very small satellites, are about 12 miles (20 kilometers) in diameter from both poles. However, at their equators, their diameters extend out further than the polar diameters: from between 3.7 to 6.5 miles (6.0 to 10.5 kilometers) further.

Such a shape gives them a UFO shape, at least to us humans on Earth.

The tiny moonlets, Pan and Atlas, are thought be astronomers to have formed from the icy particles that make up the Saturnian rings. Rocky planets generally form from small particles that coalesce (clump) together to make planetesimals, and maybe eventually full-fledged planets like Earth or smaller dwarf planets like Pluto.

U.S. planetary scientist Carolyn C. Porco, from the Space Science Institute, Boulder, Colorado, is one of the scientists investigating the origins of Pan (designated Saturn XVIII and S/1981 S 13) and Atlas (designated Saturn XV and S/1980 S 28), along with moonlet Daphnis (designated Saturn XXXV and S/2005 S 1).

Porco and her colleagues found that the ridges of the two moonlets are aligned with the rings around Saturn, which lends credence to the theory that they formed from those orbiting ice particles. They also found that Pan and Daphnis are composed of about one-half to two-thirds of light, porous icy materials, just like the ring particles.