November 17, 2011
The biggest, most long-lasting Saturnian storm seen by either NASA's Cassini or Voyager spacecraft roils the atmosphere of the gas giant in this nearly true-color mosaic of Cassini images.
See Encircling a Giant and Chronicling Saturn’s Northern Storm to learn more about the size and development of this storm. This mosaic shows the storm's effects encircling the planet and was created using 126 images taken in succession as different parts of Saturn's northern hemisphere rotated into Cassini's view.
Images taken using red, green and blue spectral filters are usually combined to create a natural color view. Because visible red light images were not available, images taken using a spectral filter sensitive to wavelengths of near-infrared light centered at 752 nanometers were used in place of red. So the color is close to natural color, but is not exact.
A second version of this mosaic is also included here. This view uses these same nearly true color filters, but the images were contrast enhanced. The result is a view that increases the visibility of features.
The head of the storm is near the center of the mosaic, and a train of vortices appears as blue spots just to the south of the head. These blue spots are parts of the storm's tail that have already encircled the planet and are approaching from the west (left in the image). The blue color indicates they have some high, semi-transparent haze but no thick clouds underneath because there are no white- or yellow-colored clouds shown here.
This mosaic covers an area ranging from about 18 degrees north latitude to 47 degrees north latitude. The views stretch the whole longitude range, passing through 360/0 degrees west longitude near the far right of the mosaics.
The images were obtained with the Cassini spacecraft narrow-angle camera on March 6, 2011, over about 11 hours (about a Saturnian day) at a distance of approximately 2 million miles (3.3 million kilometers) from Saturn and at a sun-Saturn-spacecraft, or phase, angle of 83 degrees. These mosaics are simple cylindrical map projections, defined such that a square pixel subtends equal intervals of latitude and longitude. At higher latitudes, the pixel size in the north-south direction remains the same, but the pixel size (in terms of physical extent on the planet) in the east-west direction becomes smaller. The pixel size is set at the equator, where the distances along the sides are equal. This map has a pixel size of 28 miles (45 kilometers) at the equator.
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. NASA’s Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena manages the mission for NASA's Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging team is based at the Space Science Institute, Boulder, Colo.
Credit: NASA/JPL-Caltech/Space Science Institute