Changes in Uranus’s rings - August 24, 2007
We saw them when Voyager flew past in 1986, but pictures of Uranus’s rings are clearly pretty enough to have everyone salivating again. Also, the planet’s rings seem to have changed since then, as Scientific American notes. Every 42 years the rings align edge-on to Earth, allowing astronomers a glare-free view. Comparing new images from ground-based telescopes to images from the Voyager flyby researchers report in Science that “dust distribution within the system has changed significantly since the 1986 Voyager spacecraft encounter and occurs on much larger scales than has been seen in other planetary systems”.
As the BBC notes, this data and images from the Hubble Space Telescope which looked at Uranus earlier this month could even reveal new moons. “Two little satellites called Cordelia and Ophelia straddle the brightest ring, the epsilon ring, and keep it in place, but people have always assumed there must be a bunch more of these satellites that are confining the nine other narrow rings. This is the unique viewing geometry that only comes along once in 42 years, when we have a chance of imaging these tiny satellites, because normally they are lost in the glare of the rings.” said Mark Showalter from the Seti Institute in California in the press release.
Come December 7 though we do get another shot - the Uranian equinox, where “the rings are perfectly edge-on to the sun, and after that, there is a brief period again when we will view the dark side of the rings, before they become illuminated again for another 42 years,” notes study author, Heidi Hammel of the Space Science Institute in Boulder, Colorado.
The press release for this study is remarkably exhaustive. This is really all about the pretty pictures though – thoughtfully provided both by the press release and the Hubble Site.
Image: Keck II images of Uranus in 2004, 2006 and 2007 / Courtesy Imke de Pater, Heidi B. Hammel, W.M. Keck Observatory
