After just a few days ago a picture of Enceladus, the icy giant, was released by NASA, now Cassini delivers stunning picture of Saturn’s moon Dione.
Cassini is definitely earning its weight in gold, as they say, for all the groundbreaking work he’s doing for us around Saturn. Just last week it gave us never before seen sights of Enceladus, one of the smaller of Saturn’s 62 moons we discovered so far, completely covered in ice and shining brightly as it reflects all the sunlight it can get.
And now it’s Dione’s turn in the spotlight. She resembles Enceladus, being covered in ice herself. She was discovered by the Italian astronomer Giovanni Cassini, for whom the spacecraft now orbiting Saturn was named. Also, she was baptized after the Greek Titaness Dione. She was Aphrodite’s mother and one of Zeus’ ancient wives.
In size, Dione is equivalent to just 0.088 out of the earth’s size. It gracefully orbits Saturn from a distance of roughly 378 000 km. She’s made mainly of water, with a small silicate rock core. Just like most of the other Saturnian moons, Dione has an extremely cratered surface.
Interesting enough, Dione sports a very light atmosphere made of oxygen ions, which was detected first by Cassini, back in 2010. But it was so thin that astronomers could’ve hardly called it an atmosphere, so it was dubbed an “exosphere”. Unfortunately, however, the multitude of water molecules in the background, which mainly come from Saturn’s Ring E, made it impossible to detect any water ice on her surface, so the source of the oxygen remains unknown for now.
The first pictures we ever received of the beautiful and cold Dione came to us in 1980 and 1981, from the Voyager 1 and Voyager 2 space probes. They passed by Saturn on their mission towards the outer Solar System. But since then, no other space probe or spacecraft has gone near her, until Cassini paid her a visit just now.
Another interesting fact Cassini learned during his visit was the fact that Dione is possibly more geologically active than we previously thought. NASA now believes Dione’s core has tidal heating, which increases when the moon gets closer to Saturn. Because of this internal heating, it is possible that she also has a liquid water ocean, underneath all that ice, just like some other of Saturn’s moons, Enceladus and Europa.
Liquid water might, of course, be an environmental habitat for potential ET life.
Image Source: www.wikipedia.org