Carolyn Porco/NASA

Carolyn Porco/NASA

NASA

NASA/JPL-Caltech/Space Science Institute

NASA/JPL-Caltech/Space Science Institute

NASA/JPL-Caltech/Space Science Institute

NASA/JPL-Caltech/Space Science Institute

NASA/JPL-Caltech/Space Science Institute

NASA/JPL-Caltech/Space Science Institute

NASA/JPL-Caltech/Space Science Institute

Even as it nears a sad end in September, the Cassini spacecraft is continuing to delight as it makes some of its final orbits through the Saturn system. As part of these "ring-grazing" maneuvers, the spacecraft has just returned the best-ever images of the small, walnut-shaped moon Pan.

The moon, which has a diameter of about 35km and is one of the innermost satellites in the Saturn system, orbits in the Encke Gap. Carolyn Porco, imaging lead for the Cassini mission, shared some of the images Thursday on Twitter, noting "Pan in mind-blowing detail with its unmistakable accretionary equatorial bulge." (All of the raw images can be found here).

In earlier research, Porco and other planetary scientists have suggested that Pan, as well as Daphnis and some of the other small moons in the Saturn system, were once denser cores that had about one-third to one-half their present size. These cores were perhaps shards left over from other collisions. Over time these cores opened gaps in the rings and subsequently have gathered ring material at their equatorial regions. This material appears to have bunched up at the equator not due to gravity, but rather to forces of the moon's rotation.

For Pan, this accretionary equatorial bulge is most distinctive in the new images—even for the scientists. "I, too, thought when I first saw these pics they must be an artist's depiction and not real," Porco tweeted. "They are real! Science is better than fiction." Indeed.

Listing image by Carolyn Porco/NASA