Planetary scientists have discovered that magnetic tornadoes on Jupiter, resulting from the interaction of magnetic lines of force, lead to the formation of giant anticyclones. These structures absorb ultraviolet light and are of a size commensurate with the Earth. Anticyclones appear as dark ovals, visible only in ultraviolet light, and are formed from thick clouds in the planet’s stratosphere.
These formations were first noticed in the late 1990s at the poles of Jupiter using the Hubble telescope. They were subsequently confirmed by NASA’s Cassini spacecraft during a flyby near the planet in 2000. However, the mechanism of their formation remained a mystery until recently.
Discovery of the mechanism of anticyclone formation
A team of planetologists led by Troy Tsubota of the University of California, Berkeley, found that magnetic vortices were the cause of these phenomena. They are formed by friction between magnetic lines of force in Jupiter’s ionosphere and the plasma torus created by the volcanic activity of the moon Io. These vortices propagate into the stratosphere, forming a thick fog that absorbs ultraviolet light.
Observations collected by the Outer Planet Atmospheres Legacy (OPAL) project, led by Amy Simon of Goddard Space Flight Center, have analyzed the dynamics of dark ovals. Images of Jupiter taken by the Hubble telescope between 2015 and 2022 showed that dark ovals appear more often at the planet’s south pole than at its north pole.
Polar phenomena and their relation to the magnetic field
As on Earth, Jupiter’s magnetic field is concentrated at the poles. As a result, auroras, visible on Jupiter only in the ultraviolet spectrum, appear. The scientists hypothesized that the dark ovals were also related to the magnetic field, although their mechanism is slightly different.
Together with researchers Tom Stallard from Northumbria University and Xi Zhang from the University of California, Santa Cruz, the team was able to confirm the theory about magnetic tornadoes. They believe these phenomena raise vortices in the atmosphere, creating dense fog. However, it is still unclear whether this fog is actually formed by the action of vortices or is a consequence of chemical processes in the lower atmosphere.
Properties and duration of dark ovals
Studies show that the fog near the dark ovals is about 50 times denser than Jupiter’s normal atmosphere. They appear for a few months and dissipate in a few weeks. The lack of correlation with the activity of charged particles indicates a more complex dynamics of the formation of these phenomena.
Dark ovals are a regular phenomenon, confirming the existence of “magnetic tornado alley” on Jupiter, a phenomenon that continues to be of interest and requires further research.
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Provided by berkeley.edu
