A team of astronomers from the University of Leicester (UK) has discovered a second Great Spot on Jupiter, rivaling the planet’s famous Great Red Spot and created by the powerful energies exerted by the great planet’s polar auroras.
This second Great Spot is 24,000 kilometers long and 12,000 kilometers wide and is located in the upper atmosphere of the planet. It is quite cold, hence the experts decided to call it the “Great Cold Spot” .
“This is the first time that a meteorological feature in Jupiter’s upper atmosphere has been observed away from the planet’s bright auroras. The Great Cold Spot is much more volatile than the slowly changing Great Red Spot. It dramatically changes in shape and form. size for only a few days and weeks , but it has reappeared since we have data to track it for over 15 years, suggesting that it is continually reforming and consequently could be as old as the auroras that form it, perhaps many thousands of years, “explains Tom Stallard, leader of the work.
Discovering the ‘Great Cold Spot’
Astronomers used the CRIRES instrument on Chile’s Very Large Telescope (VLT) to observe the spectral emissions of H3 + , a hydrogen ion present in large quantities in Jupiter’s atmosphere, which allowed scientists to map the temperature. and average density of the planet’s atmosphere. They then used images of the H3 + emission from Jupiter’s ionosphere taken by the NASA InfraRed Telescope Facility between 1995-2000 to compare the two data.
Through the combination of more than 13,000 images taken over more than 40 nights by NASA’s Infrared Telescope at the Hawaii Observatory, astronomers identified the presence of the Great Cold Spot as a dark area among the hot environment of the high Jupiter’s atmosphere.
“What is surprising on Jupiter is that, unlike Earth’s weather systems, the Great Cold Spot has been observed at the same location for 15 years, comparable to weather systems in Jupiter’s lower atmosphere, such as the Great Red Spot. The two main differences are, firstly, that Earth’s aurora sees dramatic changes caused by the Sun’s activity, while Jupiter’s auroras are dominated by gases from the volcanic moon Io, which are relatively slow and constant, and the atmospheric fluxes generated by the aurora conduct heat rapidly across the planet, causing the upper atmosphere to ring like a bell, trapping this energy closer to the poles, “Stallard clarifies.
Scientists have certainly been surprised by this discovery, but there are indications that other features could also exist in Jupiter’s upper atmosphere.
“From Earth, we hope to gain a much better understanding of this weather system in the next few years,” concludes Stallard.
The study has been published in the journal Geophysical Research Letters.
