Tracking a Propeller July 8, 2010 NASA’s Cassini spacecraft
captured a propeller-shaped disturbance in one of Saturn's rings
created by a moon that is too small to be seen here. The moon,
likely about a kilometer (half a mile) across, is invisible at
the center of the image. However, it is larger than many other
"propeller" moons and has cleared ring material from the dark
wing-like structures to its left and right in the image.
Disturbed ring material closer to the moon reflects sunlight
brightly and appears like a white airplane propeller. This
propeller appears in the A ring, which is the outermost of
Saturn’s main rings. Taken in 2006, this image is part of a
growing catalogue of "propeller" moons that, despite being too
small to be seen, enhance their visibility by creating larger
disturbances in the surrounding fabric of Saturn's rings.
Cassini scientists now have tracked several of these individual
propeller moons embedded in Saturn's disk over several years.
These images are important because they rep