In 1980 and 1981 NASA's Voyager 1 and 2 space probes passed for the first time over the planet Saturn, located 1,500 million km from the Sun. Among their numerous discoveries they observed a strange, hexagon-shaped structure in the planet's uppermost clouds surrounding its north pole. The hexagon remained virtually static, without moving, vis-à-vis the planet's overall rotation that was not accurately known. What is more, the images captured by the Voyager probes found that the clouds were moving rapidly inside the hexagon in an enclosed jet stream and were being dragged by winds travelling at over 400 km/h.
Thirty years later –the equivalent of one Saturn year, in other words, the time the planet takes to go all the way around the Sun– and over more than six consecutive years, astonomers from various countries, were able to observe Saturn's northern polar region in detail once again and confirmed that the hexagon continued in place.