Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2017 January 21
See Explanation.  Clicking on the picture will download
 the highest resolution version available.

Daphnis the Wavemaker
Image Credit: Cassini Imaging Team, SSI, JPL, ESA, NASA

Explanation: Plunging close to the outer edges of Saturn's rings, on January 16 the Cassini spacecraft captured this closest yet view of Daphnis. About 8 kilometers across and orbiting within the bright ring system's Keeler gap, the small moon is making waves. The 42-kilometer wide outer gap is foreshortened in the image by Cassini's viewing angle. Raised by the influenced of the small moon's weak gravity as it crosses the frame from left to right, the waves are formed in the ring material at the edge of the gap. A faint wave-like trace of ring material is just visible trailing close behind Daphnis. Remarkable details on Daphnis can also be seen, including a narrow ridge around its equator, likely an accumulation of particles from the ring.

Participate: Take an Aesthetics & Astronomy Survey
Tomorrow's picture: space falcon


< | Archive | Submissions | Index | Search | Calendar | RSS | Education | About APOD | Discuss | >

Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
NASA Official: Phillip Newman Specific rights apply.
NASA Web Privacy Policy and Important Notices
A service of: ASD at NASA / GSFC
& Michigan Tech. U.