To the eye alone, the colors of one of the moons of Saturn are subtle
One hemisphere of Tethys is almost pure white — the result of a steady “snow” of ice grains from one of Saturn’s rings
The other hemisphere is tinted light yellow by radiation trapped in Saturn’s magnetic field.
Tethys is Saturn’s fifth-largest moon. It’s about 660 miles wide.
The red arcs were discovered in images from the Cassini spacecraft
They’re in the northern half of the hemisphere that always faces away from Saturn.
Scientists aren’t sure just why the arcs are red
Saturn tags along with the Moon, which is almost at last quarter
Saturn looks like a bright star, directly above the Moon at first light.