A Polar Maelstrom on Venus
Wired Top Stories Download time: Sep 24 2010 7:15 AM ET
The long-sought double hurricane at Venus' south pole has disappeared. New images from ESA's Venus Express spacecraft show that the so-called polar vortex, which was thought to swirl steadily around the planet's poles at all times, is actually a chaotic maelstrom.
A gigantic hurricane with two calm, dark eyes was discovered at Venus' north pole by the Pioneer Venus spacecraft in 1979. This double-eyed feature, dubbed the "dipole of Venus," was thought to form when warm air from the planet's equator rose and traveled toward the pole, where it cooled and sank to form a deep, swirling atmospheric pit.
For decades, astronomers expected to find a similar vortex at Venus' south pole. While Venus itself rotates slowly, just once every 117 Earth days, its atmosphere whips around the planet once every four Earth days. This "super-rotating" atmosphere ought to form massive storms at both poles, astronomers reasoned.…
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