Although Saturn’s moons Dione (near) and Enceladus (far) are composed of nearly the same materials, Enceladus has a considerably higher reflectivity than Dione. As a result, it appears brighter against the dark night sky. This image was taken by NASA’s Cassini spacecraft in visible light with the narrow-angle camera on 8 September 2015.
Saturn’s 698-mile-wide moon Dione crosses the face of the giant planet in a phenomenon known as a transit. Transits play an important role in astronomy and can be used to study the orbits of planets and their atmospheres, both in our solar system and in others. By carefully observing and timing transits, scientists can more precisely determine the orbital parameters of planetary moons.
A pockmarked, icy landscape looms beneath NASA’s Cassini spacecraft in new images of Saturn’s moon Dione taken during the mission’s last close approach to the small, frozen world. Two of the new images show the surface of Dione at the best resolution ever. Cassini passed 295 miles (474 kilometres) above Dione’s surface at 7:33pm BST on 17 August 2015.
While not bursting with activity like its sister moon Enceladus, the surface of Saturn’s moon Dione is definitely not boring. Some parts of the surface are covered by linear features, called chasmata — bright icy cliffs among myriad fractures — which provide dramatic contrast to the round impact craters that typically cover moons.
NASA’s Cassini spacecraft will zip within 295 miles of Saturn’s moon Dione on Monday, 17 August — the final close flyby of this icy satellite during the probe’s long mission. After close flybys of other moons in late 2015, Cassini will depart Saturn’s equatorial plane to begin a year-long setup of the mission’s grand finale: repeatedly diving through the space between Saturn and its rings.
Like graffiti sprayed by an unknown artist, unexplained narrow, arc-shaped, reddish streaks are visible on the surface of Saturn’s icy moon Tethys in new, enhanced-colour images from NASA’s Cassini spacecraft. The red arcs are among the most unusual colour features on Saturn’s moons to be revealed by Cassini’s cameras.
© 2019 Pole Star Publications Limited