15 February 2010

The incredible thinness of Saturn's rings

When Saturn's "appendages" disappeared in 1612, Galileo did not understand why. Later that century, it became understood that Saturn's unusual protrusions were rings and that when the Earth crosses the ring plane, the edge-on rings will appear to disappear. This is because Saturn's rings are confined to a plane many times thinner, in proportion, than a razor blade. In modern times, the robot Cassini spacecraft orbiting Saturn now also crosses Saturn's ring plane. A series of plane crossing images from 2005 February was dug out of the vast online Cassini raw image archive by interested Spanish amateur Fernando Garcia Navarro. Pictured above, digitally cropped and set in representative colors, is the striking result. Saturn's thin ring plane appears in blue, bands and clouds in Saturn's upper atmosphere appear in gold. Since Saturn just passed its equinox, today the ring plane is pointed close to the Sun and the rings could not cast the high dark shadows seen across the top of this image, taken back in 2005. Moons appear as bumps in the rings.
This is today's Astronomy Picture of the Day from NASA.


  1. I was reading about Saturns rings because of this post and saw this recent post on Cassini interference pattern.

  2. The link is to some other picture now, the current picture of the day rather than the picture of Saturn's rings. I was curious about the text in the link, because it doesn't make any sense without naming one more object: Saturn's rings, in proportion to Saturn itself, are thinner than a razor blade in proportion to [the unnamed object). An apple? A watermelon? Earth?

  3. GK - link fixed. Thanx for the heads-up.

    The analogy in the text is an awkward way of saying that the thickness of the rings in proportion to their area (in the x and y planes vs the z-plane thickness, if you will) is similar to that ratio in a razor blade. I agree that it's phrased badly; probably written by a scientist rather than an English major.


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