When the Solar Wind Crushed Jupiter: A 12-Terawatt Aurora

By the end of this article, you will understand how a violent solar storm crushed Jupiter’s magnetic shield, triggering a massive ultraviolet light show, and what this tells us about space weather.

In late 2022, NASA’s Juno spacecraft was orbiting Jupiter when a massive shockwave from the Sun arrived. This was a rare event. Juno’s instruments detected the outer edge of Jupiter’s magnetic shield—the magnetosphere—collapsing inward under the intense pressure of the solar wind. At the exact same time, Juno’s ultraviolet camera was watching the southern aurora. The Surprise: As the shield crushed inward, Jupiter’s ultraviolet auroras exploded in brightness, hitting a staggering 12 Terawatts of power. That is six times brighter than the baseline level! The timing proved that a powerful interplanetary shock literally squeezed the giant planet’s magnetic field, forcing a massive light show in the process.

Original Paper: ‘Jupiter’s UV auroral response to a magnetospheric compression event’

The auroral brightening was likely caused by a solar wind shock compressing the magnetosphere.
— Dr. R. S. Giles

To understand this, we have to Build a Fence: This is NOT like a simple light bulb turning on because a switch was flipped. Think of Jupiter’s magnetic field like a giant, invisible balloon. When the solar wind hits it hard, the balloon compresses. The Salient Idea here is that this compression dramatically changes the flow of plasma and electric currents thousands of miles above the planet. The energy from that ‘squeeze’ funnels down the magnetic field lines and crashes into Jupiter’s atmosphere, creating the brilliant ultraviolet light. Interestingly, the light show did not peak the very second the squeeze happened; it took about 4 hours for the energy to fully trigger the main aurora.

It is not a simple circuit; it is a delayed, massive magnetic squeeze.
— Science Team

Here on Earth, our auroras (the Northern Lights) are intimately connected to the exact same process. When the Sun releases a burst of energy, it compresses Earth’s magnetic shield, sending charged particles raining down to create beautiful green and pink skies. Jupiter is doing the same thing, just on an unimaginably larger scale. However, Jupiter also creates its own auroras internally, driven by volcanic material from its moon Io. Cycling on the subject, this specific 2022 event proves that despite its internal power, Jupiter’s biggest, brightest ultraviolet auroras are still highly vulnerable to the whims of extreme space weather and solar wind shocks.

Extreme worlds teach us about the physics of planetary survival and magnetic protection.
— NorthernLightsIceland.com Team

How do you measure a magnetic shield collapsing? The scientists used a brilliant combination of tools on the Juno spacecraft. They used the JADE instrument to count charged particles, which spiked when Juno crossed out of the magnetic shield and into the solar wind. They also used the UVS (Ultraviolet Spectrograph) to take wide pictures of the aurora. Because Juno’s orbit has shifted over the years, the spacecraft was perfectly positioned far to the south, giving it a continuous, unblocked view of the entire southern aurora without the planet’s rotation getting in the way. It is a masterpiece of orbital timing.

The Juno mission allows us to simultaneously compare the compression state of the magnetosphere with the total UV auroral power.
— Research Authors

Q: What is a Terawatt, and how bright is Jupiter’s aurora?
A: A Terawatt is one trillion watts. Jupiter’s aurora reached 12 Terawatts during this event, which is thousands of times more powerful than the brightest auroras we see on Earth!

Q: Did the Sun cause this Jupiter aurora?
A: Yes! While Jupiter generates some of its own auroras using material from its moons, this specific extreme brightening was triggered by a massive shockwave of solar wind hitting the planet.