Astronomy Picture of the Day - 2010 February 15: Cassini e o plano dos anéis de Saturno

Cassini Spacecraft Crosses Saturn's Ring Plane 

Credit: Cassini Imaging Team, ISS, JPL, ESA, NASA 

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Explanation: If this is Saturn, where are the 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."

Astronomy Picture of the Day, NASA (Archive, 2010 February 15)