The Great Dark Spot |Tweet|The Great Dark Spot The Cassini
spacecraft has photographed an extraordinary dark cloud on
Jupiter twice as big as Earth itself. March 12, 2003: For more
than a century astronomers thought that the Great Red Spot was
the biggest thing on Jupiter. Not anymore. Images from NASA's
Cassini spacecraft have revealed something at least as large.
The Great Dark Spot. "I was totally blown away when I saw it--a
dark cloud twice as big as Earth swirling around Jupiter's north
pole," says Bob West, a planetary scientist at the Jet
Propulsion Laboratory. Right: This composite of Cassini ultra-
violet (UV) images reveals the "Great Dark Spot" swirling near
Jupiter's north pole. Jupiter's auroral zone is denoted by the
blue curve. [more] West has been chasing this cloud for some
time. He first saw it--"just a glimpse," says West--in an
ultraviolet (UV) picture of Jupiter taken by the Hubble Space
Telescope in 1997. But it only appeared in one image out of many
spanning a period of years. "I didn't