Vortices of the Outer Planets

Jupiter's Great Red Spot

The picture below, taken by NASA's Voyager 1 spacecraft on 25 February 1979, shows Jupiter's Great Red Spot. This is a large vortex which measures 14,000 km in the north-south direction and 40,000 km in the east-west direction.

The Great Red Spot (GRS) is known to exist since the invention of the telescope (in 1610), hence it is a rather stable vortex. The image below shows a series of pictures of the Great Red Spot obtained by the Hubble Space Telescope between 1992 and 1999, showing that the GRS changes in shape, size and colour over the years.

Neptune's Great Dark Spot and Dark Spot 2

The image below shows the Great Dark Spot (GDS) on Neptune, as viewed by NASA's Voyager 2 spacecraft on August 1989. The GDS lies at 22 degrees south, has largest axis about 10,000 km, moves westward with a speed of 325 m/s, and rotates counter-clockwise.

Another vortex, Dark Spot Two (DS2), can be seen at the bottom of the above image. DS2 moves eastward with some 20 m/s, i.e. in the opposite direction of the GDS, as can be seen from these two pictures, taken with an interval of 1 Neptunian day:

Images of Neptune taken with the Hubble Space Telescope (HST) on June 27-29, 1994, show no clear sign of either GDS or DS2. Whether this means that both sports have completed vanished is not known. The above images and text are taken from the web site of the Vortex Dynamics Group at Eindhoven University of Technology. More images and information on these vortices can be found at this site.