In the last few days as it's rounded periapsis in its current orbit of Saturn, Cassini has taken a lot of great photos of Saturn's moons. One series of photos was taken from pretty close to Janus, a moon about a third the diameter of Enceladus that orbits between the F and G rings. And among those, several were taken with the moon sitting in front of Saturn.
Clearly, this is Saturn, and its rings, and if you look closer you can see a tiny circle, on top of the rings, which is Mimas, and two stars in the background. It should look weird to you that while the rings are bright, Mimas is a black dot. What is happening here? Nearly everything in this picture is lit by light that has not arrived directly from the Sun.
Last month I posted a preliminary version of a slide I was working on for use in my public presentations, a slide that contains everything in the solar system bigger than 400 kilometers across, and invited comment. I've listened to all of your comments and corrections and come up with a second version.
Since Cassini currently orbits Saturn within the plane of Saturn's rings, it has lots of chances to catch two or more moons in the same photo. One such "mutual event" happened on September 17, featuring four moons: Titan, Dione, Pan, and Pandora.
I've got some lovely pictures from Saturn to show you! Every three months, the Cassini mission dumps gigabytes worth of precious Saturn data into the Planetary Data System, and the latest gift came on April 1. This particular pile of data, which was taken between April 1 and June 30, 2010, contains a lot of really terrific moon observations.
Daniel Macháček has reached into the dark side of Prometheus and pulled out an incredible amount of detail where the potato-shaped moon is illuminated by Saturnshine. He produced an animation that morphs among the three sets of four-filter color images that Cassini snapped during the flyby.
Just in time for today's Deep Impact press briefing, which you can watch on NASA TV in a few minutes: I've updated my montage of all the asteroids and comets that have been visited and photographed to include Hartley 2.
The Cassini Raw Images Website always offers rewards to the browser. This evening I found the raw images necessary to create this color composite, showing the hazy orange moon Titan, the mid-sized icy moon Dione, and the tiny rock Prometheus all at the same time.