Geek Trivia: The reigning wind

Which of the various extraterrestrial cyclones found in our solar system -- a list which includes both Jupiter's Great Red Spot and Saturn's Dragon Storm -- produces the fastest winds?

Which of the various extraterrestrial cyclones found in our solar system -- a list which includes both Jupiter's Great Red Spot and Saturn's Dragon Storm -- produces the fastest winds?

The fastest winds ever observed in our solar system were created by Neptune's Great Dark Spot (GDS), which produced wind speeds in excess of 1,500 mph (2,400 kph). That's almost 10 times faster than the minimum wind speeds necessary for a terrestrial cyclone to qualify as a Category 5 Hurricane on the Saffir-Simpson Scale. 1,500 miles per hour is also five times faster than the highest wind speeds ever observed in a terrestrial tornado, which is to say five times faster than fastest winds ever seen on Earth.

It should be noted that the GDS's solar system-best wind speeds occurred at the edge of the GDS. In fact, the highest wind speeds in all the great planetary "spot" storms occur on their edges, as the interiors of these spots are usually stagnant air masses. In the case of the GDS, scientists theorize this storm as a massive hole in the methane cloud deck of Neptune, literally a great empty spot in the atmosphere similar to the hole in Earth's ozone layer. Those theories may never be confirmed, as the GDS disappeared before the Hubble Telescope was scheduled to observe it in 1994.

However, the GDS -- and its record-setting winds -- may still rage on Neptune as a "conventional" cyclone somewhere beneath the visible cloud layer, having dissipated its great empty center. Meanwhile, a very similar phenomenon has since appeared in Neptune's northern hemisphere, creating an extraterrestrial cyclone known as the Northern Great Dark Spot.

Finally, when referring to the windy record-breaker, scientists would prefer you be specific and call it Neptune's Great Dark Spot or, even more precisely, Neptune's Great Dark Spot of 1989. That's not just because Neptune has since developed a new GDS, but because Jupiter has one as well -- and it might be bigger than the Great Red Spot.

Jupiter's GDS was first observed in 2000 by the Cassini probe. It appears and disappears for months at a time, unlike the multi-century lifespan of the Great Red Spot. Moreover, Jupiter's Great Dark Spot sits above the planet's northern pole -- where's it's not so easily observed. Also, it's invisible to the naked eye, appearing only under ultraviolet inspection. But when you see Jupiter's GDS, it's usually twice the diameter of Earth and can grow even larger -- to diameters that eclipse even the Great Red Spot.

That's not just some astonishing astronomic observation; it's a meteorologically mind-boggling moment of Geek Trivia.

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