So far, only one other moon is known that pulls its tracks in a ring gap: The 25-kilometer Pan is located in the more than 300 kilometers wide Encke gap, which is also within the A-ring. Two other moons, Prometheus and Pandora, are referred to as "Shepherd Moons" because they hold the material of the F-ring on the track.
Because the edge of the Keeler gap has strange wavy and spiky structures, planetary scientists have suspected since the first Cassini photos from last July that there is a moon there. "The visible effect that this moon has on the ring will allow us to determine its mass and examine our ideas of how rings and moons interact, " says Carl Murray of Queen Mary University of London.
If mass and size are known, the density of the new satellite can also be calculated.
Perhaps the new Trabant is highly porous, as are some of the outer, small Saturn moons, for example Atlas, Prometheus and Pandora.
"The Saturn moons embedded in the rings are among the system's most interesting celestial bodies, " says Carolyn Porco, head of a research team at the Space Science Institute, which analyzes the Cassini images. "Through these moons we can learn how once the planets arose out of the gas and dust of the Solar Mist." Display