In astronomy, Prometheus can refer to many things. It is an inner Moon of Saturn and an asteroid. Each of these objects will be discussed in this article.
Saturn's potato-shaped moon Prometheus is rendered in three dimensions in this close-up from Cassini. Credit: NASA/JPL/Space Science Institute
Prometheus, the Saturnian moon, was discovered in 1980 in photos taken by the Voyager 1 probe. It was initially designated S/1980 S 27. It is also designated Saturn XVI. It was named in 1985 after the Greek god. As moons go, this is a small example. It is elongated and measures about 119x 87x 61 km. It has several impact crater, ridges, and valleys. Some of the craters are as large as 20 km diameter. Based on its very low density and relatively high albedo(.6), scientists believe that it is a very porous icy body. Prometheus is located in the inner edge of Saturn’s F-ring. Images from the Cassini probe show that its gravitational field creates disturbances in the F Ring as the moon accretes material from it and leaves a dark channel in its wake. Since Prometheus orbits Saturn more rapidly than the material in the F ring, each new channel is carved about 3.2 degrees in front of the previous one. In 2008, further dynamism was detected, suggesting that small unseen moons orbiting within the F Ring are continually passing through its narrow core because of perturbations from Prometheus. Prometheus’s orbit appears to be chaotic, as a consequence of a mean motion orbital resonance with Pandora.
The F Ring is the outermost discrete ring of Saturn and perhaps the most active ring in the Solar system, with its features changing every few hours. It is located 3,000 km beyond the outer edge of the A-ring and was discovered in 1979 by Pioneer 11. It is just a few hundred kilometers wide, and is held together by two moons, Prometheus and Pandora. Closeup images from the Cassini probe show that it consists of one core ring and a spiral strand.
The asteroid 1809 Prometheus is an object that very little is known. It is a small main belt asteroid that has never been studied beyond its discovery. Given the large number of main belt objects, it may never be studied unless it happens do do something spectacular such as be ejected from the belt. I wish I could give you more information, but none is available.
We have written many articles about Prometheus for Universe Today. Here’s an article about Prometheus, the Michaelangelo of Saturn, and here’s an article about how Prometheus pulls on Saturn’s F Ring.
Want more resources on asteroids? Here’s NASA’s Lunar and Planetary Science Page on asteroids. And here’s Hubblesite’s News Releases about Asteroids.
We have recorded two episodes of Astronomy Cast about asteroids. There’s Episode 55: The Asteroid Belt, and here’s Episode 29: Asteroids Make Bad Neighbors.
Comments on this entry are closed.