I had ideas for umpteen blogs. Here is where they all somehow converge and I attempt to do something productive with my sprawling web presence.
Wednesday, September 10, 2014
Saturn's F ring moons have the keen eyes of scientists fixed
The Los Angeles Times reported Sept. 9, that scientists have been keeping a keen eye on Saturn’s F ring lately. For some reason the F ring, which is one of Saturn’s most chaotic and outermost rings, seems to be quickly changing and scientists do not know why.
Mini moons form and are then directly destroyed on a consistent basis and in a matter of months inside the rings. Sometimes creation and destruction occurs in the span of mere weeks. These time periods are in extreme contrast to what seems to be the norm of many, if not most, processes in space which take place over millions or billions of years.
The F ring is much more narrow than the other rings, despite its being possibly hundreds of miles wide. Most of Saturn’s rings are made up of boulder-sized pieces of ice but the F ring is mostly made up of ice particles and specks of dust (being known as the ‘dusty ring’).
The small particles of ice and dust can create “small moonlets” if they come together. This happens in the other rings, as well, though the effect is a little different. When ice and particles stick together in the F ring, they can form mountain-sized moons. However, since these ‘little’ moons are made up of ice, they can also be easily destroyed when the gravitational pull from other moons, such as Prometheus, draws near.
NASA’s Cassini spacecraft, along with the Hubble telescope, Voyagers I and II, and Pioneer 11 have been taking photographs of Saturn and its rings for quite some time now. The F ring, in particular has been shown to be in a state of constant change. Some parts of the ring are very bright, while others are barely visible at all. Portions of brightness and dimness interchange at intervals. Bright parts of the ring never stay that way for more than three months. And, though this state of constant change is typical for the F ring, it seems that the rate at which that change has been occurring has been decreasing over time.
Scientists believe that the change possibly depends on how the moon Prometheus interferes with the rings. The rate at which the moon interferes with the F ring takes place about every 17 years. Sometimes the moon is much closer to the rings than others, making a stronger pull on the rings than it does when it is farther away. When the pull is very strong, the moonlets disperse and create more of a concentration of ice and particles in one area of the ring, which when reflected, causes a significantly brighter area in the rings than usual.
Scientists believe that Cassini will start capturing more of those significantly brighter areas over the next few years. However, if areas of brightness happen less frequently, scientists will have to rethink their theories. “If it turns out they continue to decrease over time, that implies there were a lot more in the past,” said Robert French, a SETI Institute researcher who wrote an important paper recently about the F ring.
Scientists are trying to figure out if the F ring is new or old. It could be that the ring is fairly new in comparison with the others. If a very large ice moon had disintegrated, it could have created such a ring. French said that if that was the case, it could be that the F ring is going through some changes and therefore, not having much consistency or reason in that change. If scientists see pictures of the ring a few years from now and it hasn’t really changed, then that would point to the ring being very old. Scientists would love to find out if the ring is billions of years old or hundreds of years young. In order to find that out, they will need more data. It seems that a bit of patience is in order. . .
*originally published on the now defunct Examiner.com