Cassini Has Just Taken the Best Picture of Daphnis Yet!
Hello, Daphnis! On January 16, 2017, the Cassini spacecraft captured the best photo yet of Daphnis, a 5-mile-wide shepherd moon that orbits Saturn inside the Keeler Gap at the outermost edge of the A ring (and also just so happens to be my personal favorite moon of Saturn!) The raw image arrived on Earth today, and it’s just beautiful.
Daphnis is very small, and in previous images captured by Cassini over the 13 years it’s been in orbit around Saturn Daphnis has been at best just a few pixels across. It would be quite unremarkable, really, were it not for the dramatic effect it has on the ring material at the edges of the Keeler Gap. Small as it is, Daphnis still has enough of a gravitational pull to draw the fine icy particles of the rings into mile-high waves that rise both above and below the rings as it passes along. Daphnis isn’t only a shepherd, but it’s also quite the sculptor!
For once we get to see some of the detail of Daphnis’ surface, thanks to Cassini’s new ring-grazing orbits—the penultimate part of its “grand finale” that will end this September with a dive through the rings themselves and into Saturn’s atmosphere.
The little moon appears to have long ridges running across its horizontal width, with smooth slopes perpendicular to them. You can also make out what seems to be a very fine trail of ring material arcing up near it, and also what could be small flecks of reflective bits trailing behind it (although I don’t know for sure if those are actual objects or image artifacts.)
I’ve loved images of Daphnis ever since I started blogging about space exploration back in 2009, so this is a big highlight for me. *Waves at Daphnis* Hi!
ADDED 1/19: Here’s an image of the disturbance left in the edge of the Keeler Gap from Daphnis’ passing. Check out those ragged lines and granular texture! Click the image for the full size.
UPDATE 3/21/18: I used some of Emily Lakdawalla’s tips on accessing uncompressed raw images in Photoshop to work on a higher-quality version of the image seen above. Here’s my latest attempt at Daphnis, a cropped and colored version of Cassini’s green channel image…you can see a bit more detail in the rings and in the edge of the Keeler Gap that’s being pulled toward the moon: