In this infrared view of the South Pole of Venus, the yellow area at the bottom is the daylit side of the planet. The two "eyes" of the polar vortex appear as red blobs near the pole (at center of image). Part of the cold collar that surrounds the polar vortices is visible in blue on the night side (upper half) of the image. Click on image for full size (65 Kb) Image courtesy ESA/VIRTIS/INAF-IASF/Obs. de Paris-LESIA.

Venus has odd, swirling vortices in its atmosphere above each of the planet's poles. These vortex structures were first detected over the North Pole by NASA's Pioneer Venus Orbiter in 1978. The European Space Agency's (ESA) Venus Express discovered, and has been observing, vortices over the South Pole since it went into orbit in April 2006.

Polar vortices are actually common features on planets with atmospheres. A polar vortex forms in the winter at each pole on Earth. Saturn, too, has polar vortices. The vortices on Venus are peculiar because they are double vortices; each polar vortex has two "eyes" which the winds and clouds swirl around. Scientists don't fully understand the Venusian vortices and are continuing to study their behaviors.

Large, bright clouds periodically form over the poles. The clouds sometimes appear and dissipate within a few hours. These bright clouds can increase the albedo of the polar atmosphere by 30% as they reflect more sunlight back into space. Some scientists think that upwelling of sulfur dioxide from the lower atmosphere, stirred by the polar vortices, creates these clouds.

The polar vortices on Venus are surrounded by "collars" of colder air. These collars may form some sort of boundary between the polar vortices and the flow of the atmosphere at lower latitudes. Venus, like Earth, has a Hadley cell atmospheric circulation pattern on either side of the equator. The Venusian Hadley cell extends nearly to the poles, reaching about 60° north and south latitude (as compared to ~30° on Earth). The cold collars appear between about 60° and 70° latitude.

Venus has high-speed winds in its upper cloud deck, about 60-70 km (37-43 miles) above the planet's surface. At equatorial latitudes these winds rip along at 360 km/hr (224 mph). Poleward of 50° latitude the wind speeds quickly decline, dropping to zero at the poles.

The surface temperatures on Venus are extremely high, around 464° C (867° F). The incredibly dense atmosphere spreads this heat evenly over the surface and keeps it very steady through time. The nighttime side of the planet is just as hot as the daytime side, and poles of Venus are just as scorching hot as the equator. The spin axis of Venus is tilted a mild 3° (compared to Earth's 23°). Due to this minimal tilt and the thick atmosphere, there are no seasons on Venus. Wherever you go... and whenever you go... on Venus, you can count on it being hot!

This picture shows the South Pole of Venus. It was taken in infrared light. The yellow area at the bottom is the daytime side of the planet which is lit by the Sun. The two "eyes" of the polar vortex are the red blobs near the pole (at the center of the picture). Click on image for full size (65 Kb) Image courtesy ESA/VIRTIS/INAF-IASF/Obs. de Paris-LESIA.

A vortex is a swirling, circular movement of air and clouds... like in a tornado or hurricane. The plural form of vortex is "vortices". The planet Venus has vortices in its atmosphere above each of its poles. A NASA spacecraft spotted vortices above the North Pole in 1978. A spacecraft from the European Space Agency (ESA) found vortices at the South Pole in 2006.

Some other planets have polar vortices. A polar vortex forms in the winter at each pole on Earth. Saturn also has polar vortices. The polar vortices on Venus are unusual. Each polar vortex has two "eyes" that the winds and clouds swirl around. The vortices on Venus are double vortices. Scientists aren't quite sure why Venus has these odd double vortices.

Sometimes large, bright clouds form over the poles of Venus. They often form and go away pretty quickly. These clouds reflect a lot of sunlight back into space. They make Venus look much brighter. Scientists think the vortices "stir up" the atmosphere, causing the clouds to form.

Venus has a very dense, very hot atmosphere. The thick atmosphere spreads the heat around evenly. It is just as hot on the nighttime side of Venus as it is on the daytime side. On Earth, the poles are much colder than the equator. On Venus, it is just as hot at the poles as it is near the equator. The spin axis of Venus is not tilted very much, so Venus doesn't really have seasons. It is always hot on Venus... in both the summer and the winter.

This picture shows the South Pole of Venus. It was taken in infrared light. The yellow area at the bottom is the daytime side of the planet which is lit by the Sun. The two "eyes" of the polar vortex are the red blobs near the pole (at the center of the picture). Click on image for full size (65 Kb) Image courtesy ESA/VIRTIS/INAF-IASF/Obs. de Paris-LESIA.

A vortex is a swirling, circular movement of air and clouds... like in a tornado or hurricane. The plural form of vortex is "vortices". The planet Venus has vortices in its atmosphere above each of its poles.

Some other planets have polar vortices too. A polar vortex forms in the winter at each pole on Earth. Saturn also has polar vortices. The polar vortices on Venus are strange. Each polar vortex has two "eyes" that the winds and clouds swirl around. The vortices on Venus are double vortices. Scientists don't really know why the vortices on Venus have two "eyes".

Sometimes large, bright clouds form over the poles of Venus. They often form and go away pretty quickly. These clouds reflect a lot of sunlight back into space. They make Venus look much brighter. Scientists think the vortices "stir up" the atmosphere. Maybe that mixing makes the clouds.

The atmosphere on Venus is very thick and very, very hot. The thick atmosphere spreads the heat around. On Earth, the North Pole and the South Pole are much colder than the equator. On Venus, it is just as hot at the poles as it is near the equator.