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Cassini Provides New View of Saturn’s Wave-Making Moon Daphnis

A new image from NASA’s Cassini spacecraft shows Saturn’s small moon Daphnis and the waves it raises in the surrounding ring material.

This image was obtained in visible light with the Cassini spacecraft narrow-angle camera on January 16, 2017, at a distance of about 17,000 miles (28,000 km) from Daphnis. Image credit: NASA / JPL-Caltech / Space Science Institute.

This image was obtained in visible light with the Cassini spacecraft narrow-angle camera on January 16, 2017, at a distance of about 17,000 miles (28,000 km) from Daphnis. Image credit: NASA / JPL-Caltech / Space Science Institute.

Daphnis, also known as S/2005 S1, is approximately 5 miles (8 km) across.

It was first seen in images taken by Cassini in May 2005, as the spacecraft began its climb to higher inclinations in orbit around Saturn.

Daphnis occupies an inclined orbit within the 26-mile (42-km) wide Keeler Gap in Saturn’s outer A ring.

It orbits 85,000 miles (136,500 km) from the gas giant, completing one orbit in 14 hours.

The moon’s gravitational pull perturbs the orbits of the particles forming the gap’s edge and sculpts the edge into waves that have both horizontal and vertical components.

Like Saturn’s other small ring moons, Atlas and Pan, Daphnis appears to have a narrow ridge around its equator and a fairly smooth mantle of material on its surface — likely an accumulation of fine particles from the rings.

An additional ridge can be seen further north that runs parallel to the equatorial band.

Fine details in the rings are also on display in this image.

In particular, a grainy texture is seen in several wide lanes which hints at structures where particles are clumping together.

In comparison to the otherwise sharp edges of the Keeler Gap, the wave peak in the gap edge at left has a softened appearance.

This is possibly due to the movement of fine ring particles being spread out into the gap following Daphnis’ last close approach to that edge on a previous orbit.

A faint, narrow tendril of ring material follows just behind the tiny moon.

This may have resulted from a moment when Daphnis drew a packet of material out of the ring, and now that packet is spreading itself out.