PASADENA, Calif. — Scientists working with the Cassini spacecraft have released the first of what promises to be multiple movies of Jupiter’s dynamic atmosphere, captured by the probe as it flies by the gas giant while en route to Saturn.

The brief movies were shot, as it were, in early October. Each shows a fat chunk of Jupiter equal to about one-quarter of the planet’s circumference.

The first film covers seven separate 10-hour rotations of Jupiter, but focuses on the planet’s Great Red Spot, its best-known and most immediately recognizable feature.

The spacing of the movie frames in real time is not uniform. Indeed, some consecutive frames are divided by a single rotation of the planet, others by two.

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The movie clearly shows the eastward and westward zonal jets that circle Jupiter at the same latitude. Neither the speed nor the direction of the jets has changed over the last century.

Even more long-lived is Jupiter’s Great Red Spot -- the ovoid shape visible in the lower right corner of the frame — as it has been from Earth ever since humans first trained telescopes on the planet 400 years ago. In the film, Jupiter’s atmosphere flows counterclockwise around the Spot, with visible details as small as 300 miles (500 kilometers) across.

Also apparent to the left of the Great Red Spot are at least two smaller bright clouds that scientists believe to be lightning storms. Eventually, the storms merge with the Red Spot and surrounding jets, perhaps supplying them with energy. As Cassini swings past the planet and its dark side comes into view, the probe will be on the lookout for flashes of lighting within the storms.

The second clip shows a smoothed view of the opposite side of Jupiter seen in the first film.

The clip shows a similarly sized swath of the planet captured during the same seven rotations as the film above. However, to smooth the sequence of stills, scientists used wind profile data on the planet’s zonal atmosphere to even out the time steps between frames. Thus, the final clip includes both real and false frames.

Visible in the film is Jupiter’s white oval, the result of the recently consummated merger of three similar features that had persisted in the planet’s atmosphere for 60 years. Like the Great Red Spot, the oval is a high-pressure center, although it is only half as large. Toward the end of the sequence, the shadow of the Jovian moon Europa pops up in the frame.

Future Cassini films of Jupiter should be longer in length and of higher resolution.

Cassini will keep Jupiter’s rings, moons and, occasionally, its atmosphere in its sights through January 15, 2001, at which point the spacecraft will be looking back on a crescent Jupiter from a distance of 11 million miles (18 million kilometers).

At that time, the Cassini imaging team will return to making repeated images of the planet itself as the spacecraft speeds toward Saturn. They hope Cassini will capture its last Jupiter images on March 22, 2001.

As Cassini cruises by the solar system's largest planet, it is teaming up with the Galileo probe currently orbiting Jupiter to make an unprecedented series of joint observations of the planet. While Galileo is approaching the end of its mission, Cassini is just now getting going. It should arrive at Saturn in 2004 to begin its primary mission -- an intensive study of the planet, along with its complex system of rings and moons.