Photography ... astronomy ... art ... design ... technology
(... and the odd rant)

All of these make my world go 'round, to some extent, and they will all be found here at some time or other. Some of the photography can be purchased from my Redbubble site. I can also be found at Tempus Fugit (no longer being updated).

Thursday, April 16, 2009

Distant shadows

Astronomical imaging technology has come a long way since I first looked at Saturn through a small telescope, some time around 1973. Pioneer and Voyager spacecraft brought us the Ringed Planet from a vantage point outside of Earth's orbit for the first time, and presented breathtaking views of ring details, strange 'spokes', new rings and extra Saturnian satellites. Lately, Cassini has taking an extended look, and brought more detail and revelations, including a backlit Saturn with new, diffuse very faint rings much further out from the main rings.

Currently, Saturn's rings are being viewed almost edge-on to Earth and the Sun, which happens only twice in each 29-year orbit. When it does happen, we can see things that are normally hidden by the rings, such as some of the smaller satellites (and their shadows) passing in front of the giant planet. From the privileged vantage point enjoyed by Cassini, we are able to look down on the planet and its ring system, as in this image. As well as the sheer fascination of seeing such fine detail in the ring structure and the shadow of a satellite, there's a new treat: shadows from the rings themselves.

Jagged Shadows May Indicate Saturn Ring Particles

Much of the ring system seems to be composed of flat, uniform rings of differing width and brightness. Some rings are known to appear like twisted rope, and are separated from the main rings, as they are affected by small nearby satellites. In this case, we seem to be looking at a ring which is directly adjacent to others, but which seems to have definite thickness and texture, and which splits in two. The thickness is evident from the lumpy shadow cast on the other rings, and is a reminder that even with something as well-observed as Saturn, new surprises are still lurking.

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