Cassini snaps Saturn’s Tethys using ultraviolet, green and infrared spectral filters
Ever since NASA’s Cassini reached Saturn, it has been providing stunning images of the gaseous giant and its moons. Recently the spacecraft captured Tethys using its ultraviolet, green and infrared spectral filters and the result was a composite that shows one of the largest impact craters on Saturn’s icy moon in greater clarity.
Taken from a distance of approximately 186,000 miles (300,000 kilometers) from Tethys, the image was acquired on May 9, 2015. The image shows the giant impact basin Odysseus as it stands out brightly from the rest of the illuminated icy crescent. Tethys’ dark side (at right) is faintly illuminated by reflected light from Saturn.
NASA says that the distinct coloration of the impact basin may result from differences in either the composition or structure of the terrain exposed by the giant impact. Odysseus, which is 280 miles across, is one of the largest impact craters on Saturn’s icy moons, and may have significantly altered the geologic history of Tethys.
Mother & Daughter
In Greek mythology, Dione was the daughter of Tethys, so we should perhaps not be surprised to see the two eponymous moons together.
In reality, the moons Tethys (660 miles or 1062 kilometers across) and Dione (698 miles or 1123 kilometers across) are not mother and daughter in any sense. They are perhaps more like sisters since scientists believe that they formed out of the same disk around an early Saturn.
Dione in this image is the upper moon, while Tethys is the lower.
This view looks toward the anti-Saturn side of Dione. North on Dione is to the right. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on April 4, 2015.
The view was obtained at a distance of approximately 1.5 million miles (2.4 million kilometers) from Dione. Image scale is 9 miles (14 kilometers) per pixel.