- Original Caption Released with Image:
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Wind-blown clouds and haze high in Saturn's atmosphere are captured in a
movie made from images taken by the Cassini narrow angle camera between
Feb. 15 and Feb. 19, 2004.
The bright areas in these images represent high haze and clouds near the
top of Saturn's troposphere. Cassini has three filters designed to sense
different heights of clouds and haze in the planet's atmosphere. Any
light detected by cameras using the 889-nanometer filter is reflected
very high in the atmosphere, before the light is absorbed.
This is the first movie ever made showing Saturn in these near-infrared
wavelengths. The images were made using a filter sensitive to a narrow
range of wavelengths centered at 889-nanometers, where methane in
Saturn's atmosphere absorbs sunlight.
In the movie, atmospheric motions can be seen most clearly in the
equatorial region and at other southern latitudes. Saturn's equatorial
region seems disturbed in the same way that it has been for the past
decade, as revealed by observations from NASA's Hubble Space Telescope.
Researchers have speculated that the bright cloud patterns there are
associated with water-moist convection arising from a deeper atmospheric
level where water condenses on Saturn, and rising to levels at or above
the visible cloud tops. Close analysis of future data by scientists on
the Cassini-Huygens mission should help determine whether this is the
case.
Saturn's rings are extremely overexposed in these images. Because the
range of wavelengths for this spectral filter is narrow, and because
most of this light is absorbed by Saturn, the disc of Saturn is
inherently faint and the exposures required are quite long (22 seconds).
The rings do not strongly absorb at these wavelengths, so they reflect
more light and are overexposed compared to the atmosphere. Orbiting moons
in the images were manually removed during processing. The movie,
consisting of 30 stacked images, spans five days and captures five
complete but non-consecutive Saturn rotations. The direction of motion
is from left to right. Each 10.6-hour Saturn rotation is evenly sampled
by six images. After each rotation sequence, the planet can be seen to
grow slightly in the field of view. Cassini was 65.6 million kilometers
(40.7 million miles) from Saturn when the images, reduced in scale by a
factor of two onboard the spacecraft, were taken. The resulting image
scale is approximately 786 kilometers (420 miles) per pixel.
The Cassini-Huygens mission is a cooperative project of NASA, the
European Space Agency and the Italian Space Agency. The Jet Propulsion
Laboratory, a division of the California Institute of Technology in
Pasadena, manages the Cassini-Huygens mission for NASA's Office of
Space Science, Washington, D.C. The imaging team is based at the Space
Science Institute, Boulder, Colorado.
For more information, about the Cassini-Huygens mission visit,
http://saturn.jpl.nasa.gov and the Cassini imaging team home page,
http://ciclops.org.
- Image Credit:
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NASA/JPL/Space Science Institute
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