NASA released this image this week of two very different moons of the planet Saturn. The moon at the top of the image is Pandora. It’s small as Saturn moons go, only 50 miles (81 km) across, and it’s elongated and irregular in shape. The moon at the bottom of the image is Mimas, 246 miles (396 km) across. Mimas is considered a medium-sized moon of Saturn, and it’s large enough to have pulled itself into a the shape of sphere via its own self-gravity. These two moons typify the sorts of objects we have found throughout our solar system … and, no doubt, will find orbiting distant suns as well. NASA said in an October 13, 2015 statement about this image:
The shapes of moons can teach us much about their history. For example, one explanation for Pandora’s elongated shape and low density is that it may have formed by gathering ring particles onto a dense core.
This view looks toward the unilluminated side of the rings from 0.26 degrees below the ring plane. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on July 26, 2015.
The view was obtained at a distance of approximately 485,000 miles (781,000 kilometers) from Pandora. Image scale is 3 miles (5 kilometers) per pixel. Mimas is 904,000 miles (1.4 million kilometers) from the spacecraft in this image. The scale on Mimas is 5.4 miles (8.4 kilometers) per pixel.
Bottom line: Cassini image of two Saturn moons, Mimas and Pandora.
Deborah Byrd created the EarthSky radio series in 1991 and EarthSky.org in 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. "Being an EarthSky editor is like hosting a big global party for cool nature-lovers," she says.