Category Archives: Saturn
The lines of Saturn’s rings appear to get sharply bent as their reflected light passes through the upper atmosphere of the planet before being captured by Cassini’s camera in this raw image, acquired on June 9, 2016.
Enormous Saturn of course is, by volume, nearly all atmosphere with a solid core only about the size of Earth. The bands of tans, blues, purples and pale greens we see in Cassini images are just the tops of clouds, and even more transparent layers of atmosphere exist above those, gradually fading out into space. Like what astronauts see from orbit when the Moon passes behind these upper layers, getting squished in the process, Saturn’s rings appear to be distorted by the same refractive process for Cassini. It’s literally an optical illusion, as obviously the rings aren’t changing shape at all!
The image above has been cropped and rotated for artistic effect; see the original raw image here.
A crowning achievement of the Cassini mission to Saturn is the discovery of water vapor jets spraying out from Enceladus‘ southern pole. First witnessed by the spacecraft in 2005, these icy geysers propelled the little 320-mile-wide moon into the scientific spotlight. After 22 flybys of Enceladus during its nearly twelve years in orbit around Saturn, Cassini has gathered enough data to determine that there is a global subsurface ocean of salty liquid water beneath Enceladus’ frozen crust—an ocean that gets literally sprayed into space. Now, new findings from Cassini and researchers at the Planetary Science Institute—with a little help from a star called Epsilon Orionis—has shown that at least some of the vapor jets get a boost in activity when Enceladus is farther from Saturn.
Drumroll please… the little moon Telesto! (You like it, you really like it!) This image, captured by Cassini on Jan. 14, 2016, shows Saturn’s moon Telesto – a “leading trojan” of the much larger satellite Tethys.
A trojan moon is one that orbits a parent body within the same path as a more massive satellite, positioned at the Lagrangian points L4 and L5… usually at 60º ahead and behind within the orbit relative to the overall center (which, in the case of Tethys, is Saturn.)
The irregularly-shaped, 15-mile (24-km) -wide Telesto rides around Saturn ahead of Tethys, making it the moon’s “leading” trojan. Its slightly larger sister Calypso follows behind Tethys as the trailing trojan. All three orbit the ringed planet at a distance of over 183,000 miles (294,000 km).
After nearly eleven and a half years in orbit around Saturn the Cassini spacecraft has made its last-ever targeted flyby of Enceladus, the 320-mile-wide moon of Saturn that has intrigued scientists and the public alike with its active water ice geysers for more than a decade since their discovery. On Saturday Dec. 19, 2015, Cassini performed its E-22 flyby of Enceladus, coming within 3,106 miles (5,000 km) of the moon’s fractured and frozen surface as it sped by at over 21,000 mph. It captured some incredible images along the way, including the one above showing a crescent-lit Enceladus from its night side silhouetted against the hazy upper atmosphere of Saturn, 150,000 miles beyond.
Take a look through some more raw images from the E-22 flyby below.
On Nov. 11, 2015, NASA’s Cassini spacecraft passed relatively closely by Saturn’s moon Tethys, one of the ringed planet’s larger icy satellites. The animation above was made from 29 raw images acquired with Cassini’s narrow-angle camera as it passed by; you can see part of the incredibly cratered and ancient surface of this 662 mile (1,065 km) wide moon. Talk about flyover country!
On Wed. Oct. 28 Cassini performed its lowest-altitude dive yet through the icy plumes of Enceladus, coming just 30 miles from the moon’s surface — that’s only about 6 times higher than a commercial airliner at cruising altitude. But, traveling over 19,000 mph relative to Enceladus (which is 38 times faster than a jet plane!) the pass was over in just a few seconds. Still, Cassini managed to capture some images before, during, and after closest approach — and they’ve arrived on Earth today.
Here are some of the raw images from the E-21 flyby. These have not been validated or made into official releases by NASA or the Cassini imaging team yet, but they are a nice teaser of what we might expect once they are. (And, of course, the science performed during the flyby has yet to be revealed.) So pics only for now!