Seventy-Day Jupiter Movie Pulls Patterns Out of Chaos

July 16, 2001


Guy Webster/JPL (818) 354-6278

Maria Martinez, Southwest Research Institute (210) 522-3305

A kaleidoscopic movie made from about 1,200 Jupiter images taken by
NASA's Cassini spacecraft reveals unexpectedly persistent polar weather
patterns on the giant planet.

QuickTime Movie (1.3 MB)

RealPlayer Movie (470 KB)

AVI movie (7.9 MB)

QuickTime Movie (1.3 MB)

RealPlayer Movie (450 KB)

AVI movie (7.5 MB)

QuickTime Movie (1.2 MB)

RealPlayer Movie (460 KB)

AVI movie (7.6 MB)

Long-lived storms and globe-circling belts of clouds are familiar
features around Jupiter's midsection, easily seen even in still pictures.
Closer to the poles, though, still images show widespread mottling that
appears chaotic.

"You'd expect chaotic motions to go with the chaotic appearance, but
that's not what we see," said the planetary scientist who put the movie
together, Dr. Ashwin Vasavada of the California Institute of Technology,
Pasadena. "The movie shows that the small spots last a long time and move
in organized patterns."

Cassini shot the images in infrared light to cut through Jupiter's upper
haze and show the clouds underneath in black and white. The movie clip
combines those images taken over a span of 70 days into a sequence less
than a minute long. The version centered on the north pole and another
version showing the entire planet are available online from NASA's Jet
Propulsion Laboratory, Pasadena, Calif., at and from the Cassini imaging
science team's site at .

Caltech planetary scientist Dr. Andrew Ingersoll, a member of the Cassini
imaging team, said the movie also gives insight into storms' duration in
Jupiter's high latitudes. "There are thousands of storms there the size of
the biggest storms on Earth," he said. "Until now, we didn't know the
lifetime of those storms." The movie shows thousands of spots bumping
into each other but generally moving together within each band of
latitude. The spots occasionally change bands or merge with each other,
but usually they last for the entire 70 days. Each spot is an active storm
in Jupiter's atmosphere.

"The smaller and more numerous storms at high latitude share many of the
properties of their larger cousins like the Great Red Spot at lower
latitudes," Ingersoll said.

The mystery of Jupiter's weather is why the storms last so long. Storms on
Earth last a week before they break up and are replaced by other storms.
The new data heighten the mystery because they show long-lived storms at
the highest latitudes, where the weather patterns are more disorganized
than at low latitudes.

"Perhaps we should turn the question around and ask why the storms on
Earth are so short lived," Ingersoll said. "We have the most unpredictable
weather in the solar system, and we don't know why."

Dr. Carolyn Porco, Cassini imaging team leader and a planetary scientist
at the Boulder, Colo., office of Southwest Research Institute, presented
the movie at a meeting of Jupiter scientists in Boulder recently. "This is
the first movie ever made of the motions of Jupiter's clouds near the
poles, and it seems to indicate that one notion concerning the nature of
the circulation on Jupiter is incomplete at best, and possibly wrong," she

The model in question suggests that Jupiter's alternating bands of
east-west winds are the exposed edges of deeper, closely-packed rotating
cylinders that extend north-south through the planet. In this
laboratory-tested model, Porco said, "many such cylinders sit
side-by-side, girdling the planet like rings of narrow solid-rockets
strapped to the outside of a larger rocket." At the planet's surface,
one would see only east and west winds, alternating with latitude and
symmetric about the equator. "However, the east-west winds that the movie
shows in the polar regions don't fit that model," Porco said. Jupiter's
wind pattern may involve a mix of rotation-on-cylinders near the equator
and some other circulation mechanism near the poles.

The movie required processing of images that Cassini took through an
infrared filter during the last three months of 2000. The position of the
spacecraft slightly north of the planet's equatorial plane gave an oblique
view of Jupiter's north pole. The images were projected into maps of the
northern hemisphere as if viewed from directly above the pole. In that
view, the high-latitude mottling becomes a concentric series of circular
bands, each rotating in the opposite direction as adjacent bands.

Cassini, launched in 1997, passed Jupiter on Dec. 30, 2000, on its way
toward its ultimate destination, Saturn. It will begin orbiting Saturn on
July 1, 2004, and drop its piggybacked Huygens probe onto the haze-wrapped
moon Titan about six months later.

More information about the Cassini-Huygens mission is available online at . The mission is a collaboration of NASA,
the European Space Agency and the Italian Space Agency. JPL, a division
of Caltech, manages the Cassini program for NASA's Office of Space
Science, Washington, D.C.

NOTE TO BROADCASTERS: A video file with the Jupiter movie sequences and
B-roll will air on July 17 at noon EDT. NASA Television is available at
GE-2, Transponder 9C at 85 degrees West longitude, with vertical polarization.
Frequency is on 3880.0 megahertz with audio on 6.8 megahertz.

Additional information about Cassini-Huygens is online at

The Cassini spacecraft is scheduled to arrive at Saturn in July 2004 to
begin a four-year exploration of the ringed planet and its moons. The
Cassini mission is managed by NASA's Jet Propulsion Laboratory in Pasadena,
Calif., for NASA's Office of Space Science, Washington, D.C. JPL is a
division of the California Institute of Technology in Pasadena.

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