A Saturnian hurricane

Captured here in false color by the Cassini spacecraft is a giant vortex spinning above Saturn’s north pole. The narrowband camera filters used to record the image reveal information about the storm’s altitude: The red projection, taken at a wavelength of 752 nm in the near-IR, reveals low clouds; the green at 728 nm and blue at 890 nm reveal high clouds. Structurally, the vortex resembles a hurricane on Earth, but on a much grander scale. With a diameter of 2000 km, the dark ring—the “eye” of the vortex—is some 50 times as wide as the eye of a typical hurricane. The bright ring of clouds surrounding it is an eyewall in which winds blow counterclockwise at 150 m/s.

Such detailed images of the north pole region have become possible only recently, now that spring has brought sunlight to the planet’s northern hemisphere. But the storm has been churning for years: Cassini’s IR spectrometers detected hints of a possible vortex shortly after the spacecraft’s arrival in 2004 during the northern winter. Cassini observed a comparably sized storm at Saturn’s south pole in 2006. (Image courtesy of NASA/JPL-Caltech/SSI.)

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