Experienced and enthusiastic observers will recall that a remarkable hexagonal storm was discovered surrounding the North Pole of Saturn by the Voyager mission in 1981 and subsequently confirmed by NASA’s Cassini probe in 2006. This extraordinary feature became slowly visible to amateur imagers after 2009 as the northern hemisphere tilted towards sunlight. Now NASA’s Juno probe has discovered cyclonic storms around Jupiter’s poles that are packed into what has been described as “remarkable polygonal patterns” (Dr. J Rogers Ph.D). The patterns were discovered by the Juno team using JunoCam (visual light) and JIRAM (Infra-red light) instruments and the results published on the 8th of March in the magazine Nature.
The patterns are described as five cyclones forming a pentagon around a central cyclone at the South Pole and eight cyclones forming a modified octagon or ‘double square’ around a central one at the North Pole. Observations from Juno suggest these are not transient features but are stable on a timescale of at least one year with only small variations in the spacing of each cyclone from each other and with some drift of the central cyclone with regard to the position of the pole. These are large features with each cyclone ranging from 5200 to 8200 Km across with the south-polar storms tending to be the largest; several times larger than terrestrial hurricanes but measurements suggest wind-speeds comparable to those found on Earth.
There is no suggestion that the Jovian cyclones are forming for the same reason as the famous Saturnian hexagon, which is a warped Jetstream surrounding one vast cyclone, and much work remains to be done to explain these new features which remain stable despite ferocious wind speeds, however it is thought these may be real examples of a laboratory modelling technique known as ‘vortex crystals’. The very high latitudes of these features makes observation of them from Earth impossible but it proves the normally bland regions of Jupiter’s polar caps are, in fact, active, full of surprises and worthy of study.