There's a mass of swirling gas and cloud located some 37 miles (60 km) above Venus's south pole. This image was captured by the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) aboard ESA's Venus Express spacecraft.
Astronomers have actually known about this vortex for quite some time. And in fact, it was one of the first discoveries made by the Venus Express Orbiter in 2006. This particular photo was captured back in 2007, but it was only released by the ESA this week.
The space agency explains the phenomenon:
Venus has a very choppy and fast-moving atmosphere – although wind speeds are sluggish at the surface, they reach dizzying speeds of around 400 km/h at the altitude of the cloud tops, some 70 km above the surface. At this altitude, Venus' atmosphere spins round some 60 times faster than the planet itself. This is very rapid; even Earth's fastest winds move at most about 30% of our planet's rotation speed. Quick-moving Venusian winds can complete a full lap of the planet in just four Earth days.
Polar vortices form because heated air from equatorial latitudes rises and spirals towards the poles, carried by the fast winds. As the air converges on the pole and then sinks, it creates a vortex much like that found above the plughole of a bath.
This particular vortex is a violent mix of warming and cooling gases, which are all surrounded by a "collar" of cool air. Be sure to check out this video of the vortex made from 10 images taken over a period of five hours.
Definitely something deserving of a closer look once we get those Venusian spaceports deployed.
[ ESA ]
Image: ESA/VIRTIS/INAF-IASF/Obs. de Paris-LESIA/Univ. Oxford