What is causing the mysterious haze at Jupiter’s poles?

Jupiter’s iconic Great Red Spot has captivated observers for centuries. Now, astronomers at UC Berkeley have identified equally intriguing Earth-sized spots at Jupiter’s poles. 

Unpredictable ovals appear at Jupiter’s poles 

Unlike the Great Red Spot, these polar ovals appear and vanish unpredictably and are only visible at ultraviolet (UV) wavelengths.What is causing the mysterious haze at Jupiter’s poles? 

These dark UV ovals, embedded in the stratospheric haze at Jupiter’s north and south poles, were observed just below the bright auroral zones – regions similar to Earth’s northern and southern lights. 

Absorbing more UV light than the surrounding areas, the ovals stand out in images captured by NASA’s Hubble Space Telescope. 

A recent systematic study of Hubble’s observations from 2015 to 2022 revealed that these southern UV-dark ovals (SUDO) appear 75% of the time at the south pole, while their northern counterparts (NUDO) were spotted only twice in 25 global maps of Jupiter’s north pole.

Unraveling the mystery at Jupiter’s poles

The discovery of these UV spots has led researchers to suspect that they are linked to Jupiter’s powerful magnetic field, which influences processes extending deep into the planet’s atmosphere. These phenomena go far beyond the surface-level magnetic interactions responsible for auroras on Earth.

The findings, led by UC Berkeley undergraduate researcher Troy Tsubota and senior astronomer Michael Wong, were recently published in the journal Nature Astronomy. 

Their analysis builds on observations that date back to the late 1990s when Hubble first detected dark UV ovals at both poles. 

The north pole ovals were also observed by NASA’s Cassini spacecraft during its flyby of Jupiter in 2000, but these features received little attention until now.

Systematic study of the polar spots 

Tsubota’s systematic analysis of Hubble data revealed eight distinct southern UV-dark ovals between 1994 and 2022. However, similar features at the north pole were far less common, appearing only twice in 25 maps. 

Most of the Hubble images used for this research were part of the Outer Planet Atmospheres Legacy (OPAL) project, directed by Amy Simon at NASA’s Goddard Space Flight Center. 

OPAL captures yearly snapshots of the outer planets – Jupiter, Saturn, Uranus, and Neptune – to study their atmospheric dynamics and evolution. Tsubota’s innovative approach to analyzing OPAL data proved fruitful. 

“In the first two months, we realized these OPAL images were like a gold mine,” said Tsubota. “I quickly constructed an analysis pipeline to process all the images and see what insights we could gain.”

What causes the mysterious ovals?

Collaborating with planetary atmospheric experts Tom Stallard of Northumbria University and Xi Zhang of UC Santa Cruz, the researchers developed a theory to explain these dense haze spots. 

Stallard proposed that the ovals are the result of swirling vortex dynamics originating in Jupiter’s ionosphere. 

The vortex may be driven by friction between Jupiter’s magnetic field lines and the sheet of ionized plasma surrounding the planet, which is influenced by volcanic activity on Jupiter’s moon Io.

The vortex spins most rapidly in the ionosphere, weakening as it descends into the atmosphere. At its deepest point, it stirs up the stratospheric haze, creating the dense, UV-dark ovals observed by Hubble. 

“The haze in the dark ovals is 50 times thicker than the typical concentration, which suggests it likely forms due to swirling vortex dynamics rather than chemical reactions triggered by high-energy particles from the upper atmosphere,” said Zhang. 

“Our observations showed that the timing and location of these energetic particles do not correlate with the appearance of the dark ovals.”

Jupiter’s complex atmospheric system

The research team estimates that these ovals take about a month to form and dissipate within a few weeks. This rapid lifecycle highlights the dynamic nature of Jupiter’s atmosphere and the complex interplay of forces that shape its features.

Wong emphasized that the UV ovals offer valuable insights into the connections between different atmospheric layers. 

“Studying connections between different atmospheric layers is very important for all planets, whether it’s an exoplanet, Jupiter, or Earth,” Wong said. 

“We see evidence for a process connecting everything in the entire Jupiter system, from the interior dynamo to the satellites and their plasma torii to the ionosphere to the stratospheric hazes. Finding these examples helps us to understand the planet as a whole.”

A window into planetary evolution

The discovery of these polar UV-dark ovals underscores the importance of long-term observational projects like OPAL. 

By systematically analyzing decades of data, researchers can uncover subtle but significant atmospheric features that were previously overlooked.

The findings not only enhance our understanding of Jupiter but also contribute to broader studies of planetary evolution. Similar atmospheric dynamics may exist on other gas giants in our solar system or even on exoplanets beyond it.

As researchers continue to study these enigmatic spots, their work will shed light on the mechanisms that drive atmospheric phenomena across a variety of planets, offering a richer understanding of the complexities within our solar system and beyond.

Image Credit: Troy Tsubota and Michael Wong, UC Berkeley

—–

Like what you read? Subscribe to our newsletter for engaging articles, exclusive content, and the latest updates.

Check us out on EarthSnap, a free app brought to you by Eric Ralls and Earth.com.

—–