Enceladus Backlit By Saturn
An amazing picture of Saturn, it’s barely visible edge on rings, (less than one degree above ring plane) and its moon Dione. Dione was discovered in 1684 by Cassini, and later named after the Greek goddess of the same name, the mother of Aphrodite.
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The shadows of Saturn’s rings are cast onto the planet and appear as a thin band at the equator in this image taken as the planet approached its August 2009 equinox.
Approximately every 15 years, Saturn’s experiences equinox. Just like on Earth, the equinox occurs when the Sun is directly over the equator. And because Saturn’s rings orbit around its equator, the Saturnian equinox also means that the rings are exactly edge on to the Sun.
by NASA / JPL / Space Science Institute.
Saturn’s Iapetus: Painted Moon
Credit: Cassini Imaging Team, SSI, JPL, ESA, NASA
Vast sections of this strange world are dark as coal, while others are as bright as ice. The composition of the dark material is unknown, but infrared spectra indicate that it possibly contains some dark form of carbon. Iapetus also has an unusual equatorial ridge that makes it appear like a walnut.
Pictured above, from about 75,000 kilometers out, Cassini’s trajectory allowed unprecedented imaging of the hemisphere of Iapetus that is always trailing. A huge impact crater seen in the south spans a tremendous 450 kilometers and appears superposed on an older crater of similar size.
(Source: ikenbot, via celestialtransfer)
Southern Enceladus in Radar View by Lunar and Planetary Institute on Flickr.
NASA’s Cassini spacecraft obtained these views of the south polar area of Saturn’s moon Enceladus in visible and near-visible (ultraviolet and infrared) light and synthetic-aperture radar (SAR). The region is south of 45 degrees south latitude. The SAR image, acquired November 6, 2011, is shown as an arc running from upper left to lower right, accented in light blue. Bright and dark edges of this arc are artifacts of the radar imaging process. The background image was taken with visible-light, with color added for emphasis (see below). Visible-light images, like we normally see in photographs, are mostly bright or dark depending on their target’s chemical composition, while brightness in SAR images usually depends on how rough or smooth the surface is. The SAR swath is about 15 miles (25 kilometers) wide and is centered at 65 south latitude, 295 west longitude.
The color in the background image is used to separate different materials using ultraviolet, visible and infrared images taken from 2004 to 2009. Blue colors represent icy material that originated in the plumes and fell back to the surface. Since these images were taken using illumination by sunlight, they sense ice particles and other roughness in the wavelength range of 50 to 100 microns. The SAR swath uses microwaves 2 centimeters long in wavelength to “light” the surface, so it senses roughness in that range. In addition, the SAR may be seeing that roughness slightly under the surface.