Earth-sized ovals at Jupiter's north and south poles, visible only at ultraviolet (UV) wavelengths, appear and disappear at seemingly random intervals, according to a study led by astronomers at the University of California, Berkeley.

Jupiter's dark ultraviolet ellipses are mostly located directly beneath bright auroral bands at each pole, similar to Earth's northern and southern lights.

This spot absorbs more ultraviolet light than the surrounding area, so it appears darker in images from the NASA/ESA Hubble Space Telescope.

In annual images of the planet taken by Hubble between 2015 and 2022, dark ultraviolet ellipses appear 75% of the time at the south pole, but only in one in eight images taken at the north pole. A dark oval will appear.

The dark ultraviolet ellipses suggest that unusual processes are occurring in Jupiter's strong magnetic field. This magnetic field propagates all the way to the poles and deep into the atmosphere, much deeper than the magnetic processes that produce auroras on Earth.

The dark ultraviolet ellipse was first detected in the 1990s by Hubble at the North and South poles, and later also at the North Pole by NASA's Cassini spacecraft, which flew close to Jupiter in 2000, but received little attention.

In a new analysis of Hubble images, University of California, Berkeley undergraduate student Troy Tsubota and his colleagues found that the oval shape is a common feature of Antarctica. They counted eight Southern Ultraviolet Dark Ovals (SUDOs) between 1994 and 2022.

In all 25 Hubble Earth maps showing Jupiter's north pole, only two northern ultraviolet dark ellipses (NUDOs) were found.

Most of the Hubble images were taken as part of the Outer Planet Atmospheres Legacy (OPAL).

“In the first two months, we realized that these OPAL images were kind of a gold mine. We quickly built this analysis pipeline and asked what we could get by sending all the images. We were able to confirm that,” says Tsubota.

“That's when we realized we could actually do good science and real data analysis and have conversations with our collaborators about why these things appear.”

The authors also aimed to determine the cause of these areas of dense fog.

They theorized that the dark ellipse was likely being stirred up from above by a vortex created when the planet's magnetic field lines rub at two very far apart locations. One is the friction in the ionosphere and the Earth's sheet, the rotational motion of which has previously been detected using ground-based telescopes. Hot ionized plasma around the planet emitted by the volcanic moon Io.

The vortex rotates fastest within the ionosphere and gradually weakens as it reaches deeper layers.

Like a tornado landing on dusty ground, the deepest parts of the vortex stir up the hazy atmosphere, creating the dense patches observed by astronomers.

It is unclear whether the mixing will dredge more haze from below or create additional haze.

Based on their observations, researchers believe that the oval shape may form over about a month and disappear within a few weeks.

Astronomer Dr Shih Zhang said: “The dark elliptical haze is 50 times thicker than typical concentrations. This is because this haze is due to the dynamics of the vortex, rather than a chemical reaction caused by high-energy particles from the upper atmosphere. This suggests that it is likely to have been formed by At the University of California, Santa Cruz.

“Our observations show that the timing and location of these high-energy particles do not correlate with the appearance of the dark ellipses.”

This discovery, which the OPAL project was designed to discover, will reveal how the atmospheric dynamics of the solar system's giant planets differ from what we know on Earth. .

“Studying the connections between different atmospheric layers is extremely important for all planets, whether exoplanets, Jupiter, or Earth,” said Dr. Michael Wong, an astronomer at the University of California, Berkeley.

“We see evidence of processes connecting everything throughout the Jovian system, from internal dynamos to satellites, plasma torii, ionospheres, and stratospheric haze.”

“Finding these examples helps us understand the entire planet.”

of study Published in a magazine natural astronomy.

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TK Tsubota others. Jupiter's ultraviolet to dark polar ellipse shows the connection between the magnetosphere and atmosphere. Nat Astronpublished online on November 26, 2024. doi: 10.1038/s41550-024-02419-0

This article is adapted from the original release by the University of California, Berkeley.