Clyde Foster, a retired chemical engineer and amateur astronomer from Centurion, South Africa, noticed a previously unseen spot to the south-east of the gas giant's famous storm, the Great Red Spot, through his telescope on the morning of May 31, 2020. In images captured by astronomers in Australia only a few hours prior, this feature was not visible.
Luckily, NASA’s Juno spacecraft was on hand to clear up the mystery, performing its 27th close flyby of Jupiter (Perijoves 27) just two days after Foster’s initial sighting. Although it did not journey directly over the point of interest, the spacecraft came close enough for Juno’s JunoCam instrument to provide a detailed view of the spot, informally named “Clyde’s Spot”.
“Given the timing, the fact that Juno is in a 53-day highly elongated orbit, and only able to capture a thin slice of Jupiter during flyby, it is a remarkable coincidence,” Foster wrote on the Astronomical Society of Southern Africa’s website.
As opposed to the gigantic anticyclonic storm nearby, “Clyde’s Spot” is actually a powerful convective “outbreak” – an erupting plume of gas extending above the upper cloud layers of the Jovian atmosphere. In certain filters, sensitive to wavelengths of light where methane gas is strongly absorbed, the outbreak appears as a bright patch, which signaled the existence of “Clyde’s Spot”.
These outbreaks are common in Jupiter’s North and South Equatorial belts, but in the planet’s South Temperate Belt, where this latest spot was spotted, they are much rarer. For this reason, Foster explains, astronomers have taken a keen interest in his finding.
“The images show fascinating structures within the storm system that is already causing excitement within the Planetary Science community,” Foster wrote.
Foster and the rest of the Juno mission will be waiting for the spacecraft’s next flyby on July 25, 2020, to see how the outbreak will develop. But Juno’s 53-day flybys can’t last forever, indeed in a year’s time, it will plunge into the planet’s atmosphere in one final hurrah. The spacecraft will leave behind a plethora of glorious images and incredible data of the Solar System’s largest planet.