The atmosphere of the Solar System’s largest planet continues to surprise astronomers: At Jupiter’s north and south poles, beneath the bright regions of its auroras, there are huge dark spots visible only in the ultraviolet range. Studying these Earth-sized oval structures reveals complex processes in the planet’s magnetosphere and atmosphere and could lead to more accurate models of gas giant atmospheres.

The most famous atmospheric phenomenon of the fifth planet from the Sun – the Great Red Spot – is a persistent zone of high pressure and regularly changes size. The shape and size of this atmospheric vortex varies on a 90-day cycle. However, the reasons for this are unknown.

Jupiter also has auroras: ionized gas (sulfur and oxygen ions expelled by the moon Io, as well as ionized hydrogen) emits a purple and (rarely) blue color. This extremely bright phenomenon occurs in the atmosphere of the gas giant mainly due to the planet’s extremely strong magnetic field (10-14 times greater than the Earth’s magnetic field).

Now, a research group from the University of California (USA), analyzing data obtained by the Hubble Space Telescope from 1994 to 2022, has discovered unusual oval structures at the north and south poles of Jupiter. Spots, visible only in the ultraviolet range, are seen 75 percent of the time at the South Pole but are extremely rare in the North Pole; only one in eight observations shows them.

According to the authors of the scientific study presented in the journal, the discovery Nature AstronomyIt shows that the south pole of the gas giant is more prone to processes that lead to the formation of spots. The latter almost always appears under Jupiter’s bright aurora regions, absorbing more ultraviolet radiation from the atmosphere, noted Troy Tsubota, the study’s lead author. That’s why they look darker in photos.

The team of scientists hypothesized that these mysterious structures appeared as a result of the interaction between the planet’s magnetic field and its atmosphere; This phenomenon is probably due to a strong anticyclonic vortex formed by the interaction of Jupiter’s ionosphere and the plasma thorium created by Io. As you may remember, this volcanically active satellite emits 1,000 kilograms of ionized gas per second into space, which then forms a torus surrounding the gas giant along the Moon’s orbit.

“This vortex resembles a hurricane that reaches the lower layers of the atmosphere and mixes stratospheric gases. As a result of these processes, dense hazy areas appear, which can lead to an increase in the aerosol concentration by 50 times compared to the normal level,” explained astronomer Michael Wong (Michael Wong), co-author of the study. .

The results showed that processes in Jupiter’s magnetosphere affect its atmosphere more strongly than previously thought: the interaction of magnetic fields and plasma flows leads to the emergence of dynamic processes that form eddies. The events observed by astronomers are particularly contrasting when compared to conditions on Earth; On our planet, such magnetic processes mainly affect the upper layers of the atmosphere, causing aurora borealis.

Astronomers noted that studying the connections between different layers of the atmosphere is important for understanding the atmospheric dynamics of any planet, such as Jupiter, Earth, or worlds outside the solar system (exoplanets). Further observations of the gas giant’s polar regions will help scientists learn more about the formation mechanisms of dark spots and their impact on the planet’s atmosphere.

The discovery took place within the framework of the OPAL (Exoplanet Atmosphere Legacy) program and may lead to the creation of more accurate models of planetary atmospheres in the future, allowing a better understanding of their dynamics and evolution over time.