Jupiter’s Great Red Spot may be less than 200 years old

Jupiter’s signature characteristic — its Great Red Spot — mightiness not beryllium nan aforesaid acheronian spot seen connected nan elephantine satellite much than 3 hundreds of years ago.

From 1665 to 1713, astronomer Giovanni Domenico Cassini and others observed a acheronian oval — nicknamed nan Permanent Spot — connected Jupiter astatine nan aforesaid latitude wherever nan Great Red Spot now swirls. Researchers coming person wondered whether these spots are 1 and nan same.

An study of sketches and photographs of Jupiter spanning astir 360 years suggests the spots are distinct, researchers study successful nan June 28 Geophysical Research Letters. Computer simulations from nan aforesaid study besides hint astatine nan Great Red Spot’s origin, indicating a disruption successful nan upwind betwixt opposing pitchy streams whitethorn person kick-started nan planet’s giant, ruddy storm. 

The Great Red Spot is our star system’s largest vortex (SN: 12/12/17). Located successful Jupiter’s Southern Hemisphere, nan windstorm’s gusts transcend 600 kilometers per hour. But it’s not clear really acold backmost successful clip this spot goes and what sewage it spinning.

Luckily, immoderate satellite observers of nan past sketched what they saw done their telescopes. “It was very breathtaking to spot successful aged articles and books nan descriptions of nan observations and drawings that astronomers made pinch awesome precision,” says Agustín Sánchez‐Lavega, an astronomer and planetary intelligence astatine nan University of nan Basque Country successful Bilbao, Spain.

Sánchez‐Lavega and his colleagues dug done records connected nan spots. Starting successful 1713, reports of Jupiter carnivore nary signs of nan Permanent Spot. Then, successful 1831 and nan pursuing decades, drawings show a spot resembling nan Great Red Spot — a clear oval that became red-tinted.

Measurements of nan Permanent Spot from drawings propose that it was astir one-third to one-half arsenic wide arsenic nan Great Red Spot arsenic photographed successful 1879, which astatine nan clip was astir 3 times nan width of Earth. The Permanent Spot’s absence successful nan grounds for 118 years and its mini size propose it whitethorn person vanished earlier nan Great Red Spot emerged, nan researchers conclude.

“That’s very compelling, and they’ve done a really bully job,” says Timothy Dowling, a planetary intelligence astatine nan University of Louisville successful Kentucky.

But it still isn’t clear really Jupiter’s iconic large wind came to be. Sánchez‐Lavega’s squad ran machine simulations of Jupiter’s ambiance to analyse 3 possibilities: a merger of swirling areas, nan aftermath of a elephantine thunderstorm aliases a disturbance betwixt opposing pitchy streams.

To nutrient a spot nan size of nan early Great Red Spot requires nan consolidation of vortices that are themselves arsenic ample arsenic nan Red Spot was backmost then. This is unlikely, nan squad reports, arsenic specified features would person been spotted. Meanwhile, simulations of a elephantine thunderstorm grounded to nutrient a spot arsenic ample arsenic nan early Great Red Spot.

But an area of rotation could person formed astatine this latitude betwixt a pitchy stream moving westward and 1 moving eastbound (SN: 11/3/23). A unit disturbance could person caused nan upwind to do a U-turn astatine its ends, creating a travel that curved from northbound to southbound astatine 1 extremity and southbound to northbound astatine nan other. This spinning region could person acted arsenic precursor to nan Great Red Spot, Sánchez‐Lavega says.

But nan simulations utilized to study nan elephantine windstorm’s statement don’t see thunderstorm activity, which is important to really nan Great Red Spot maintains itself, Dowling says. A ringing of thunderstorms forms astir nan satellite astatine this latitude and yet nan storms get sucked into — and fundamentally provender — nan Great Red Spot, he says. The Great Red Spot whitethorn thief seed these storms — it’s truthful large that it obstructs nan travel of state astir nan satellite astatine this latitude, creating a low-pressure region ripe for thunderstorm formation. “It’s successful a world system.”

The Great Red Spot has been shrinking since it was spotted successful nan 1800s. It’s presently 1.1 times arsenic wide arsenic Earth —about nan size of nan long-lost Permanent Spot. And it whitethorn stock that spot’s fate, Dowling says. A shriveling spot whitethorn not beryllium capable to substance capable thunderstorm activity to prolong itself. “There are immoderate group who are live correct now — immoderate younger kids — that whitethorn spot nan extremity of this one.”