Saturn Moons Align (Almost) to Perfection: Photo

Saturn moons align
(Image credit: NASA/JPL-Caltech/Space Science Institute)

NASA's Cassini spacecraft has been in Saturn orbit for over a decade and it has seen the whole spectrum of ringed planet delights. But there are few views in Saturnian orbit that are more satisfying than seeing two or more moons in the same frame — particularly when they align.

PHOTO: Cassini Watches Enceladus Fizz into Space

In this stunning example of celestial good timing on Sept. 24, Cassini snapped Enceladus drift in front of larger moon Tethys in near-perfect alignment. Interestingly, the size difference between the two moons closely reflect their relative differences in diameter. Enceladus is 313 miles (504 kilometers) across whereas Tethys is 660 miles (1,062 kilometers) across.

At the time of the moon transit, Cassini was 1.3 million miles (2.1 million kilometers) from Enceladus and 1.6 million miles (2.6 million kilometers) from Tethys, meaning the 2 moons were only approximately 300,000 miles (500,000 kilometers) apart.

NEWS: Cassini to Make Final Flybys of 2 Icy Saturn Moons

Enceladus is of huge scientific interest to NASA and the Cassini mission. Now known to contain a sub-surface ocean beneath an icy crust, the small moon is thought to possess the ingredients for life. Cassini is currently lining up for its last ever flyby of Enceladus on Dec. 19, an encounter known as E-22 (the 22nd flyby), coming within 3,106 miles (4,999 kilometers) of the moon's surface.

Source: NASA

Originally published on Discovery News.

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Media Relations Specialist, NASA's Jet Propulsion Laboratory

Ian O'Neill is a media relations specialist at NASA's Jet Propulsion Laboratory (JPL) in Southern California. Prior to joining JPL, he served as editor for the Astronomical Society of the Pacific‘s Mercury magazine and Mercury Online and contributed articles to a number of other publications, including,, Live Science,, Scientific American. Ian holds a Ph.D in solar physics and a master's degree in planetary and space physics.