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These neighboring moons look totally different: Here's why

Two of Saturn's moons step into the NASA spotlight with a Cassini image highlighting their differences.

Saturn moons
Dione sits in the foreground and Enceladus appears behind.
NASA/JPL-Caltech/Space Science Institute

Saturn has enough moons to star in a reality TV show about a ridiculously big space-family. NASA's Cassini spacecraft is hanging out in Saturn's neighborhood, imaging some of the planet's more than 60 moons. Dione and Enceladus are of particular interest, and a new Cassini image shows the pair dressed up in very different clothes.

Cassini snapped the pic in early September, but NASA released it as an Image of the Day Tuesday. It shows Dione up close and Enceladus peeking out from behind it in the distance. Dione displays a gray, crater-marked surface that looks like a round piece of pumice in space. Enceladus, on the other hand, is a bright, reflective object that looks like a space snowball.

NASA explains why these space sisters have such different looks. Enceladus gets its glow from "a constant rain of ice grains from its south polar jets." That makes it appear suitable for hosting a "Frozen" sequel. Dione has a surface that is older and weathered and has gathered dust and radiation damage. NASA calls this process "space weathering."

At 313 miles (504 kilometers) across, Enceladus is somewhat dainty compared with Dione's 689 miles (1,123 kilometers). They both rank among the largest of Saturn's moons, though Titan, a fascinating place full of mysterious vanishing islands and hydrocarbon seas, dwarfs them both at 3,200 miles (5,150 kilometers) across.

Cassini conducted flybys of both Dione and Enceladus this year, zooming by for a closer look at the orbiting objects. Cassini's scenic view comes from about 52,000 miles (83,000 kilometers) away from Dione.

Cassini launched back in 1997 for an extended mission to study Saturn and its satellites. The mission is scheduled to last until at least 2017. The spacecraft is currently investigating icy plumes noticed on Enceladus and will later move on to study some of the ringed planet's smaller moons.