![]() ![]() “That wasn’t a complete surprise,” said Connerney. This is where Saturn’s magnetic field intersects the orbit of Enceladus, a geologically active moon that is shooting geysers of water ice into space, indicating that some of those particles are raining onto Saturn as well. The team also discovered a glowing band at a higher latitude in the southern hemisphere. They found that the amount of rain matches remarkably well with the astonishingly high values derived more than three decades earlier by Connerney and colleagues, with one region in the south receiving most of it. They analyzed the light to determine the amount of rain from the ring and its effects on Saturn’s ionosphere. Their observations revealed glowing bands in Saturn’s northern and southern hemispheres where the magnetic field lines that intersect the ring plane enter the planet. When energized by sunlight, the H3+ ions glow in infrared light, which was observed by O’Donoghue’s team using special instruments attached to the Keck telescope in Mauna Kea, Hawaii. ![]() One outcome from these reactions is an increase in the lifespan of electrically charged particles called H3+ ions, which are made up of three protons and two electrons. ![]() Once there, the icy ring particles vaporize and the water can react chemically with Saturn’s ionosphere. In some parts of the rings, once charged, the balance of forces on these tiny particles changes dramatically, and Saturn’s gravity pulls them in along the magnetic field lines into the upper atmosphere. When this happens, the particles can feel the pull of Saturn’s magnetic field, which curves inward toward the planet at Saturn’s rings. Tiny particles can get electrically charged by ultraviolet light from the Sun or by plasma clouds emanating from micrometeoroid bombardment of the rings. Ring particles are caught in a balancing act between the pull of Saturn’s gravity, which wants to draw them back into the planet, and their orbital velocity, which wants to fling them outward into space. Saturn’s rings are mostly chunks of water ice ranging in size from microscopic dust grains to boulders several yards (meters) across. The influx of water from the rings, appearing at specific latitudes, washed away the stratospheric haze, making it appear dark in reflected light, producing the narrow dark bands captured in the Voyager images. In 1986, Jack Connerney of NASA Goddard published a paper in Geophysical Research Letters that linked those narrow dark bands to the shape of Saturn’s enormous magnetic field, proposing that electrically charged ice particles from Saturn’s rings were flowing down invisible magnetic field lines, dumping water in Saturn’s upper atmosphere where these lines emerged from the planet. These dark bands appeared in images of Saturn’s hazy upper atmosphere (stratosphere) made by NASA’s Voyager 2 mission in 1981. The first hints that ring rain existed came from Voyager observations of seemingly unrelated phenomena: peculiar variations in Saturn’s electrically charged upper atmosphere (ionosphere), density variations in Saturn’s rings, and a trio of narrow dark bands encircling the planet at northern mid-latitudes. The innermost rings disappear as they rain onto the planet first, very slowly followed by the outer rings. An artist's impression of how Saturn may look in the next hundred million years. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |