Mimas and Saturn in cool blue
Saturn's moon Mimas is seen against the cool, blue-streaked backdrop of Saturn's northern hemisphere, in this image from the NASA/ESA/ASI Cassini-Huygens spacecraft.
Delicate shadows cast by the rings arc across the planet, fading into darkness on Saturn's night side. The part of the atmosphere seen here appears darker and more blue than the brown and gold hues seen in earlier Cassini-Huygens images of the southern hemisphere, due to preferential scattering of blue wavelengths by the cloud-free upper atmosphere.
The bright blue swath near Mimas (398 kilometres across) is created by sunlight passing through the 'Cassini division' (4800 kilometres wide). The rightmost part of this distinctive feature is slightly overexposed and therefore bright white in this image. Shadows of several thin ringlets within the division can be seen here as well.
The dark band that stretches across the centre of the image is the shadow of Saturn's B ring, the densest of the main rings. Part of the actual Cassini division appears at the bottom, along with the A ring and the narrow outer F ring. The A ring is almost transparent so that, from this viewing angle, the atmosphere and shadows cast by the inner C ring are visible through it.
The Cassini-Huygens mission is a co-operative project of NASA, ESA and ASI, the Italian space agency.
Credits: NASA/JPL/Space Science Institute