The ESA's Venus Express spacecraft has been observing the south pole of Venus and the phenomenon that morphs and changes shape within a matter of days. It was discovered in 1974 by the Mariner 10 spacecraft.

The eye of the hurricane is at the center of a 1,200-mile-wide vortex. There is a similar structure on the planet's north pole, which was observed by the Pioneer Venus mission in 1979.

Venus Express scientists studying the structure in the thermal infrared said the core of the vortex appears very bright, probably indicating a lot of atmospheric gases are moving downward in the region, which creates a depression at the cloud-tops, making the region hotter.

Scientists aren't sure what causes the vortex but the investigation is ongoing, said Colin Wilson of the University of Oxford.

The initial discovery was reported in the journal Nature.