November 17, 2011
With kaleidoscopic forms and hues, these two false-color views from NASA's Cassini spacecraft show the patterns that come and go in the course of one Saturn day within the huge storm in the planet's northern hemisphere.
Taken about 11 hours -- or one Saturn day -- apart, these mosaics [see http://saturn.jpl.nasa.gov/photos/imagedetails/index.cfm?imageId=4407] consist of 60 images each. The top mosaic was taken on Aug. 17, 2011, while the bottom mosaic was captured on Aug. 18, 2011. Each of the two batches of images was taken over the course of about 3 hours.
A two-frame animation is also included here, scaled down from the full-size mosaics. The animation switches back and forth between the two mosaics allowing comparisons of the subtly changing cloud details. Several features in the more southern part of the storm can be seen moving to the right, or east, while several features in the more northern part of the storm can be seen moving to the left, or west.
Cassini scientists study the fine details contained in these mosaics to learn about wind speeds and cloud depths in the storm. For example, a red curlicue that indicates a deep cloud present when the top mosaic was captured may not appear at all or may have moved to a different location in the bottom mosaic taken 11 hours later.
See Encircling a Giant for similar, false-color mosaics captured in February 2011.
These views look at a more southerly latitude on Saturn than the earlier mosaics in Encircling a Giant , and these views are better centered on the storm. Whereas those earlier false-color mosaics appear more blue-green because they show more of the area surrounding the storm, these false-color mosaics show the many colors of the storm itself.
These mosaics cover an area ranging from about 22.6 degrees north latitude to 37.8 degrees north latitude. The views stretch from about 43.7 degrees west longitude on the left to 298.9 degrees west longitude on the right, passing through 360/0 degrees west longitude.
See See Chronicling Saturn’s Northern Storm to learn more about the development of this storm. to learn more about the development of this storm.
The images were taken with the Cassini spacecraft narrow-angle camera using a combination of spectral filters sensitive to wavelengths of near-infrared light. The images filtered at 889 nanometers are projected as blue. The images filtered at 727 nanometers are projected as green, and images filtered at 750 nanometers are projected as red.
The views were acquired at a distance of approximately 1.4 million miles (2.2 million kilometers) from Saturn and at a sun-Saturn-spacecraft angle (phase angle) of 62 degrees. Both the top and bottom images 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. The images have a pixel size of 11 miles (18 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