The 6 Best Cassini Images of Saturn's Moon Dione

Monday, 17 August 2015 - 5:04PM
Space
Astronomy
Space Imagery
Monday, 17 August 2015 - 5:04PM
The 6 Best Cassini Images of Saturn's Moon Dione
NASA's spacecraft Cassini has been studying Saturn and its moons since 2004, and its historic mission will finally come to an end in 2017. Today, August 17, the spacecraft will perform its fifth and final close flyby past Dione, coming within a mere 295 miles of the fractured surface.

The icy chasms on Dione's surface may indicate the presence of active geological processes, similar to Saturn's moon Enceladus, but we've never been able to study the moon closely enough to be sure. This flyby may answer longstanding questions about Dione and its composition.

Opening quote
"Dione has been an enigma, giving hints of active geologic processes, including a transient atmosphere and evidence of ice volcanoes - but we've never found the smoking gun," Bonnie Buratti, a Cassini science team member at JPL said in a statement. "The fifth flyby of Dione will be our last chance."
Closing quote


Today's mission should also yield some closer-than-ever images of Dione, which could yield insights as to the nature of those mysterious chasms. In honor of the closest flyby in history, here are six of the best Cassini images of Dione:

Wispy Terrain


The Best Cassini Images of Saturn's Moon Dione

This image, taken by Cassini on April 11, was taken in visible light approximately 68,000 miles from Dione. It revealed that the moon is covered in troughs called chasmata, which NASA classified as "wispy terrain" in the lower-resolution Voyager pictures. Cassini's research has shown that the chasmata are not surface deposits of frost, as was previously thought, but icy cliffs.

Dione sits on Saturn's rings


The Best Cassini Images of Saturn's Moon Dione

This amazing image is from the previous closest flyby on December 12, 2011, 35,000 miles from Dione. Saturn's rings, the thin diagonal line, can be seen on their northern, sunlit side. 

Rhea Flies By

The Best Cassini Images of Saturn's Moon Dione

Just as Cassini is about to fly by Dione, Rhea did a quick flyby of Saturn's moon on April 11. Dione, at 698 miles wide, is much smaller than Rhea, which is 949 miles wide, but Dione is much closer to the camera, and so appears much larger.

A close-up of Dione's surface


The Best Cassini Images of Saturn's Moon Dione

Cassini took this image on June 16 of this year, capturing Dione's cracked, pockmarked surface. The diagonal line in the upper left corner is the rings of Saturn, in the distance.

Two eyes looking at Saturn


The Best Cassini Images of Saturn's Moon Dione

This image was taken on May 27 of this year, approximately 634,000 miles from Saturn, and shows both Dione and Tethys in all their glory. Dione, the larger moon, is on the left, and their position makes the moons look like they're both turned towards the humongous Saturn.

Mother and Daughter


The Best Cassini Images of Saturn's Moon Dione

This image from April 4, 2015, was taken 1.5 million miles from Dione, and shows crescent moon views of Dione and Tethys, where Dione is the upper moon and Tethys the lower. NASA referred to this image as a "mother-daughter" picture, as Dione is the daughter of Tethys in Greek mythology.


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NASA
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