Template:POTD/2012-12-02
Two views of the rings of Saturn: the top half of the image shows the illuminated (sun-facing) side of the rings in visible light as seen by the Cassini probe, and the bottom is a simulated image constructed from radio occultation data. Color in the lower image is used to represent information about ring particle sizes, as follows: radio signals of 0.94, 3.6, and 13 cm wavelengths were sent simultaneously from Cassini through the rings to Earth. The attenuation of each signal reflects the abundance of ring particles of sizes similar to the wavelength and larger. The color purple, in much of the middle (B) ring and the inner part of the outer (A) ring, indicates few particles smaller than 5 cm are present, i.e., similar attenuation of all signals. Green and blue, in the inner (C) ring and outer part of the A Ring, indicate particles smaller than 5 cm and 1 cm, respectively, are common. White areas of the B Ring are the densest and transmit too little signal for size estimation.Photo: NASA/JPL/SSI