For the first post in my blog it’s only fitting that I explain the image in my header. I created this image around 3:00 a.m. July 2, 2004 from a series of observations of Saturn’s rings made by the Ultraviolet Imaging Spectrograph on the Cassini spacecraft. The image took on a life of its own as it was featured in many newspapers around the world, was selected as one of Time magazine’s pictures of the year of 2004, and (my favorite) was shown on The Daily Show with Jon Stewart. The image shows the outer third of Saturn’s ring system, with the Cassini Division in red at the left, and the turquoise A ring across the rest of the image. The thin red band at the right is the Encke Gap, a ~350 km wide gap that is home to a small moon, Pan, and a set of faint narrow rings not visible in this image.
There are two caveats that need to go with this image: (1) the original data is actually only a narrow strip across Saturn’s rings, and I stretched it azimuthally to make a larger and more ring-like picture. The implicit assumption of circular symmetry in this step is valid at the ~150 km resolution of the data; and (2) the red color represents the Lyman-alpha glow from interplanetary Hydrogen gas throughout the solar system shining through gaps and transparent regions in the rings. So, where it is red there is less ring material. The space beyond the edge of the ring is black instead of red because we had no data beyond the edge of the ring.