Saturn's Moon, Enceladus: Facts & Overview

Instructor: Jeff Fennell

Jeff has a master's in engineering and has taught Earth science both domestically and internationally.

Enceladus is the sixth-largest moon in Saturn's orbit. It is interesting to astronomers because there is believed to be tectonic activity on the moon. This lesson will cover the facts of Enceladus.


Of Saturn's 62 moons, Enceladus is the sixth largest with a diameter of 505 kilometers. Though it is one of Saturn's largest moons, it is still relatively small. It's only one-seventh the diameter of Earth's moon and is small enough to fit inside the borders of the state of Arizona or Colorado.

Even though its size is relatively small, the surface of Enceladus is almost completely covered with ice, which reflects more than 90% of the sunlight that falls on it. This reflection makes Enceladus one of the brightest objects in the solar system.

Enceladus was discovered by William Herschel in 1789 and visited by the Voyager 1 probe in 1980. As Voyager 2 passed Enceladus in 1981, it revealed that despite the moon's small size, a wide range of terrains were present on the surface. Areas range from old, heavily cratered surfaces to young tectonic deformed terrain, with some regions of the surface as young as 100 million years old.


Enceladus orbits 238,040 km (147,911 miles) above the center of Saturn. It takes Enceladus 33 hours to orbit Saturn once and also to rotate once. Since Enceladus' rotation and orbit are in sync, one side always faces toward Saturn. Enceladus orbits in the densest part of one of Saturn's outer rings.

Due to the size of Enceladus, scientists believe that the moon was influential in the formation of Saturn's rings. It is possible that the gravity of Enceladus continually ripped apart any rock conglomerations nearby it. This is the same way Jupiter stopped the asteroid belt from forming into a planet.


As Voyager flew by, scientists observed different types of terrains covering the surface of Enceladus. In the northern hemisphere, cratered terrain covers the surface, indicating an old, unaltered surface. Below the equator, Voyager observed a flat terrain lacking craters. The absence of asteroid impact craters implies a younger surface.

Asteroid impacts take time to occur, if there is an area with a lot of craters, this means they have accumulated over a lot of time. On the other hand, a volcanic eruption can cover impact craters with a new surface. If there are not many impact craters seen, it means the surface has not been there long enough to accumulate impacts and therefore is relatively new.

Due to the absences of craters in the south, scientists speculate that the formation of these flat areas may take only a few hundred million years to recover the surface with new material. In the image below you can see the difference in surfaces.

The northern hemisphere is littered with craters, while the south is relatively flat.

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