Since 1610, Saturn’s rings have held a special wonder for those that have viewed them. These 14 rings, which are mostly composed of frozen water with only small traces of dirt, can be anywhere from 10 meters to kilometers thick and have been found to have their own extremely thin atmosphere of Hydrogen and Oxygen. Now these rings are thought to rain down on Saturn, causing effects on the planet itself. Evidence of this was found in the 80’s when the Voyager space probes passed Saturn and noticed that there were a few dark bands going around Saturn. Recently in 2011, scientists observed the planet in near-infrared wavelengths with the W.M Keck Observatory on Mauna Kea, Hawaii and saw these same distinctive bands but only at particular latitudes. It turns out that these latitudes correspond with both the rings and Saturn’s magnetosphere.
It seems that the ionosphere may be guiding down some of the water from the rings and causing it to rain on Saturn. This can be seen because the rain is striking the ions caught in the ionosphere and reducing infra-red emissions from the atmosphere in certain wavelengths. This effect is leaving large darkened areas in what would otherwise be a planet-wide infrared glow. These darkened areas are now covering about 30 to 43 percent of Saturn’s surface from around 25 to 55 degrees latitude. The percentage of the surface that is affected is much larger than was seen by the Voyager images and suggests a whole new type of space weather may exist that has never been thought to exist. Since the rings are located 67,000 to 180,000 Km above the clouds of Saturn, this is not the same type of rain, snow, or moisture that comes from Earth clouds that usually don’t go much higher than 15 Km.
Scientists are hoping to use the Cassini mission to learn more about this phenomena. They hope to use certain cameras on the probe to better learn how the water is de-ionizing the atmosphere of Saturn. It may be interesting to find out what layers of the atmosphere are being affected and to what degree. Another interest of study is seeing how the time of day affects this process. Does the Sun cause it to primarily rain in the day or night? Perhaps solar flares are causing changes in the ionosphere which triggers this effect? Only more study will reveal yet another subtle mystery of the rings of Saturn.