Narrated video about a hurricane-like storm seen at Saturn's north pole by NASA's Cassini spacecraft. › Download video › Related video
The spinning vortex of Saturn's north
polar storm resembles a deep red rose of giant proportions surrounded by
green foliage in this false-color image from NASA's Cassini spacecraft.
Image credit: NASA/JPL-Caltech/SSI. › Full image and caption
The north pole of Saturn, in the fresh
light of spring, is revealed in this color image from NASA's Cassini
spacecraft. Image credit: NASA/JPL-Caltech/SSI. › Full image and caption
PASADENA, Calif. - NASA's Cassini spacecraft has provided scientists the
first close-up, visible-light views of a behemoth hurricane swirling
around Saturn's north pole.
In high-resolution pictures and video, scientists see the hurricane's
eye is about 1,250 miles (2,000 kilometers) wide, 20 times larger than
the average hurricane eye on Earth. Thin, bright clouds at the outer
edge of the hurricane are traveling 330 mph(150 meters per second). The
hurricane swirls inside a large, mysterious, six-sided weather pattern
known as the hexagon.
"We did a double take when we saw this vortex because it looks so much
like a hurricane on Earth," said Andrew Ingersoll, a Cassini imaging
team member at the California Institute of Technology in Pasadena. "But
there it is at Saturn, on a much larger scale, and it is somehow getting
by on the small amounts of water vapor in Saturn's hydrogen
atmosphere."
Scientists will be studying the hurricane to g
ain insight into
hurricanes on Earth, which feed off warm ocean water. Although there is
no body of water close to these clouds high in Saturn's atmosphere,
learning how these Saturnian storms use water vapor could tell
scientists more about how terrestrial hurricanes are generated and
sustained.
Both a terrestrial hurricane and Saturn's north polar vortex have a
central eye with no clouds or very low clouds. Other similar features
include high clouds forming an eye wall, other high clouds spiraling
around the eye, and a counter-clockwise spin in the northern hemisphere.
A major difference between the hurricanes is that the one on Saturn is
much bigger than its counterparts on Earth and spins surprisingly fast.
At Saturn, the wind in the eye wall blows more than four times faster
than hurricane-force winds on Earth. Unlike terrestrial hurricanes,
which tend to move, the Saturnian hurricane is locked onto the planet's
north pole. On Earth, hurricanes tend to drift northward because of the
forces acting on the fast swirls of wind as the planet rotates. The one
on Saturn does not drift and is already as far north as it can be.
"The polar hurricane has nowhere else to go, and that's likely why it's
stuck at the pole," said Kunio Sayanagi, a Cassini imaging team
associate at Hampton University in Hampton, Va.
Scientists believe the massive storm has been churning for years. When
Cassini arrived in the Saturn system in 2004, Saturn's north pole was
dark because the planet was in the middle of its north polar winter.
During that time, the Cassini spacecraft's composite infrared
spectrometer and visual and infrared mapping spectrometer detected a
great vortex, but a visible-light view had to wait for the passing of
the equinox in August 2009. Only then did sunlight begin flooding
Saturn's northern hemisphere. The view required a change in the angle of
Cassini's orbits around Saturn so the spacecraft could see the poles.
"Such a stunning and mesmerizing view of the hurricane-like storm at the
north pole is only possible because Cassini is on a sportier course,
with orbits tilted to loop the spacecraft above and below Saturn's
equatorial plane," said Scott Edgington, Cassini deputy project
scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "You
cannot see the polar regions very well from an equatorial orbit.
Observing the planet from different vantage points reveals more about
the cloud layers that cover the entirety of the planet."
Cassini changes its orbital inclination for such an observing campaign
only once every few years. Because the spacecraft uses flybys of
Saturn's moon Titan to change the angle of its orbit, the inclined
trajectories require attentive oversight from navigators. The path
requires careful planning years in advance and sticking very precisely
to the planned itinerary to ensure enough propellant is available for
the spacecraft to reach future planned orbits and encounters.
The Cassini-Huygens mission is a cooperative project of NASA, the
European Space Agency and the Italian Space Agency. JPL, a division of
the California Institute of Technology, Pasadena, manages the
Cassini-Huygens mission for NASA's Science Mission Directorate in
Washington. The Cassini orbiter and its two onboard cameras were
designed, developed and assembled at JPL. The imaging team consists of
scientists from the United States, the United Kingdom, France and
Germany. The imaging operations center is based at the Space Science
Institute in Boulder, Colo.
For more information about Cassini and its mission, visit: http://www.nasa.gov/cassini
and http://saturn.jpl.nasa.gov .
Jia-Rui Cook 818-354-0850
Jet Propulsion Laboratory, Pasadena, Calif.
jccook@jpl.nasa.gov
Dwayne Brown 202-358-1726
NASA Headquarters, Washington
dwayne.c.brown@nasa.gov
Jet Propulsion Laboratory, Pasadena, Calif.
jccook@jpl.nasa.gov
Dwayne Brown 202-358-1726
NASA Headquarters, Washington
dwayne.c.brown@nasa.gov
