NASA returns to South African amateur astronomer discovery on Jupiter

NASA’s Juno spacecraft has returned to Clyde’s Spot on Jupiter and performed another series of observations of the feature that was discovered last year by Clyde Foster of Centurion, South Africa.

“On June 2, 2020, just two days after Foster’s initial discovery, Juno provided detailed observations of Clyde’s Spot, which scientists determined was a plume of cloud material erupting above the top layers of the Jovian atmosphere just southeast of Jupiter’s Great Red Spot, which is currently about 1.3 times as wide as Earth,” NASA stated.

“These powerful convective outbreaks occasionally occur in this latitude band, known as the South Temperate Belt. The initial plume subsided quickly, and within a few weeks it was seen as a dark spot.”

NASA explained that many features in Jupiter’s highly dynamic atmosphere are short lived, but observations in April 2021 from the JunoCam revealed that nearly one year after its discovery, the remnant of Clyde’s Spot had developed into a complex structure that scientists call a folded filamentary region.

“This region is twice as big in latitude and three times as big in longitude as the original spot, and has the potential to persist for an extended period of time,” NASA said.

The developments in Clyde’s Spot detected by Juno is further excitement for Foster, as it means the feature he first spotted a year ago may be much longer-lived than initially hoped.

Foster is a retired chemical engineer who has become a passionate amateur astronomer specialising in planetary imaging.

He first noticed the new spot on the surface of Jupiter in the early hours of Sunday, 31 May 2020, while he was imaging the planet through his telescope.

Clyde’s Spot discovery image, May 2020 (via NASA)

Just 10 hours earlier, the spot had not been there. Renowned astronomy photographer Andy Casely had captured images of Jupiter from Australia which did not show the spot.

Foster explained that “outbreaks” like this are relatively rare in the particular region of Jupiter where he found it.

“It is a regular occurrence in Jupiter’s North and South Equatorial belts, but substantially rarer in this location, the South Temperate region,” he said.

It’s for this reason that his discovery generated interest in the professional-amateur planetary science community.

As luck would have it, NASA’s Juno spacecraft was set to perform its 27th close flyby of Jupiter on 2 June, just days after Foster’s discovery.

Even luckier was that Juno happened to be flying by close enough to Clyde’s Spot to get a detailed look at the phenomenon.

“The spacecraft can only image a relatively thin slice of Jupiter’s cloud tops during each pass,” the Juno team explained at the time.

“Although Juno would not be travelling directly over the outbreak, the track was close enough that the mission team determined the spacecraft would obtain a detailed view of the new feature”.

Foster said that the name—Clyde’s Spot—was coined by fellow planetary imager Paul Maxson from Arizona in the United States, and was quickly adopted by the planetary science community.

While the name remains unofficial, having the Juno team refer to it as “Clyde’s Spot” on two separate occasions on the NASA website, is as official as it gets.

“It has been an interesting year since the first detection of ‘Clyde’s Spot’, with amateur imagers and the professional planetary science community tracking its progress,” Foster told MyBroadband.

“Research is ongoing on the storm, and the latest Juno images show very interesting developments, most significantly that the structure that has developed points towards further expansion.”

Clyde’s Spot, April 2021, Jupiter – PJ33-44, by Kevin M. Gill
Clyde’s Spot, June 2020, Jupiter – PJ27-42/45/47/49/50 Map by Kevin M. Gill

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NASA returns to South African amateur astronomer discovery on Jupiter