As the ice-encrusted moon Enceladus makes it way along its orbit around Saturn it gets repeatedly squeezed by the giant planet’s gravity, like a frozen stress ball with water-filled insides. This constant squeezing and relaxing generates friction heat in the moon’s crust, which could be responsible for keeping some of its internal water liquid and spraying it out into space from long canyons that cut across its southern pole. And sometimes more ice gets shot out than at other times, forming a trail of long tendrils that stretch into the “E” ring – a hazy, diffuse doughnut around Saturn made from Enceladus’ icy exhaust.
These tendrils had been observed by the Cassini spacecraft since 2006, but only now have they been positively confirmed to be the results of specific geysers on the 318-mile-wide moon.
We’re all used to seeing fantastic images of Saturn and its family of moons from NASA’s Cassini spacecraft, which has spent the last decade in orbit around the ringed world. But every now and then Cassini aims its cameras outwards, capturing images of the sky beyond Saturn – just like we might look up at the stars from here on Earth. And while it’s not designed to be a deep-space observatory like Hubble or Subaru (or even like a modest backyard telescope, really) Cassini can still resolve many of the same stars we can easily see in the night sky… and, on April 12, 2015, it spotted something much farther away: the Sombrero Galaxy (M104), 29 million light-years distant!
Coincidentally Cassini grabbed its image of M104 exactly five years after it was imaged with Japan’s Subaru Telescope, located atop Mauna Kea.
Here’s a raw image of Saturn’s moon Iapetus, looking down on its northern hemisphere from Cassini on March 31, 2015. The moon’s signature two-toned coloration is evident as its bright icy surface is partially coated by dark material, thought to have been ejected from distant neighbor Phoebe.
Iapetus is 914 miles (1,471 km) in diameter, or about as wide as Texas and Louisiana combined. It orbits Saturn at a considerable distance of 2,212,889 miles (3,561,300 km), which is nine times farther than the Moon is from us.
Iapetus’ north pole is located just below and to the left of the centrally-peaked crater south of the brightest region in the image above. (The two prominent craters near image center are Roland and Turpin.)
After spending a couple of years in an orbit riding high over the northern pole of Saturn Cassini has swung back down alongside the planet’s ringplane, in perfect alignment to once again capture views of the icy moons that reside there. The image above is a composite made from several narrow-angle camera images acquired by Cassini on Feb. 9, 2015, showing an extended color view of Rhea as the spacecraft was heading to perform a targeted flyby of the larger haze-covered moon Titan.
Saturn’s second-largest moon, the heavily-cratered Rhea wouldn’t appear this golden to our eyes; its natural colors are much more monochromatic (i.e., grey.) But Cassini can “see” in light stretching from ultraviolet to infrared, and that added range lets us see Rhea in a new light.
At 1,600 miles (2,576 km) across Titan is by far Saturn’s largest moon – in fact it’s the second-largest satellite in the solar system. It’s also the only world besides Earth where liquids have been found in large amounts on the surface, in the form of lakes and streams of frigid methane and ethane. This makes Titan an intriguing subject of study for planetary scientists, but unfortunately it’s not all that easy to get a good look at its surface because of its thick orange clouds and dense atmosphere.
Now, researchers have developed a “despeckling” method to smooth out Cassini’s typically grainy radar maps, giving scientists a whole new way to look at Titan’s alien — yet surprisingly Earth-like — surface.
This incredible image was captured ten years ago today, on January 14, 2005. It shows the murky surface of Saturn’s moon Titan as seen by the European Space Agency’s Huygens probe after it made its historic descent through the moon’s thick haze and clouds and landed in a frozen plain of crusty methane mud and icy pebbles. During the descent and after landing Huygens returned data for several hours before communication was lost. The groundbreaking images and information it sent back has proved invaluable to scientists studying this unique and mysterious moon, which is at the same time extremely alien and surprisingly Earth-like.
“It was eerie…we saw bright hills above a dark plain, a weird combination of light and dark. It was like seeing a landscape out of Dante.”
– Jonathan Lunine, Cassini-Huygens mission scientist
Learn more about the Huygens landing here and check out an incredible video below zooming in a billion times from Saturn orbit to Titan’s surface: