NASA’s Cassini spacecraft has explored Saturn and its many moons since June 2004. Many of the mission’s highlights come from close encounters with these moons including Titan, Enceladus, Dione and many others.
Cassini’s latest image takes a step back to appreciate all of Saturn.
Jupiter is the biggest planet in our solar system, but Saturn is no slouch. Its diameter comes in at just over 72,367 miles. That’s nearly 10 times the size of Earth.
See the tiny dot on the bottom right? That’s Tethys. It’s Saturn’s fifth largest moon and is about 32% the size of Earth’s moon.
The imaging team upped the brightness of Tethys by a factor of 2 to make it easier to see. Here’s a close-up of Tethys the spacecraft snapped back in April.
“The red arcs really popped out when we saw the new images,” said Cassini participating scientist Paul Schenk at the time. “It’s surprising how extensive these features are.”
What’s causing the red streaks? Scientists aren’t exactly sure. Several theories include exposed ice with some kind of chemical impurities. Speculation also centers around outgassing. These reddish features aren’t typically seen on Saturn’s other moons, except Europa.
One fact the Cassini team knows for sure is that the reddish features are geologically young. “The red arcs must be geologically young because they cut across older features like impact craters, but we don’t know their age in years,” said Paul Helfenstein, a Cassini imaging scientist.
Cassini is now in its last full year of operations. On September 15, 2017, the spacecraft will enter Saturn’s atmosphere, and its mission will come to an end. But before that, Cassini will keep gathering science and beaming it back to scientists on Earth. On Friday (Jan. 15), the spacecraft will soar 2,372 miles above Titan in a close flyby.