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By NASA
Explore This Section Overview Science Science Findings Juno’s Orbits Spacecraft People Stories Multimedia JunoCam Images Jupiter hosts the brightest and most spectacular auroras in the Solar System. Near its poles, these shimmering lights offer a glimpse into how the planet interacts with the solar wind and moons swept by Jupiter’s magnetic field. Unlike Earth’s northern lights, the largest moons of Jupiter create their own auroral signatures in the planet’s atmosphere — a phenomenon that Earth’s Moon does not produce. These moon-induced auroras, known as “satellite footprints,” reveal how each moon interacts with its local space environment.
Juno capturing the marks on Jupiter of all four Galilean moons. The auroras related to each are labeled Io, Eur (for Europa), Gan (for Ganymede), and Cal (for Callisto). NASA/JPL-Caltech/SwRI/UVS team/MSSS/Gill/Jónsson/Perry/Hue/Rabia Before NASA’s Juno mission, three of Jupiter’s four largest moons, known as Galilean moons — Io, Europa, and Ganymede — were shown to produce these distinct auroral signatures. But Callisto, the most distant of the Galilean moons, remained a mystery. Despite multiple attempts using NASA’s Hubble Space Telescope, Callisto’s footprint had proven elusive, both because it is faint and because it most often lies atop the brighter main auroral oval, the region where auroras are displayed.
NASA’s Juno mission, orbiting Jupiter since 2016, offers unprecedented close-up views of these polar light shows. But to image Callisto’s footprint, the main auroral oval needs to move aside while the polar region is being imaged. And to bring to bear Juno’s arsenal of instruments studying fields and particles, the spacecraft’s trajectory must carry it across the magnetic field line linking Callisto and Jupiter.
These two events serendipitously occurred during Juno’s 22nd orbit of the giant planet, in September 2019, revealing Callisto’s auroral footprint and providing a sample of the particle population, electromagnetic waves, and magnetic fields associated with the interaction.
Jupiter’s magnetic field extends far beyond its major moons, carving out a vast region (magnetosphere) enveloped by, and buffeted by, the solar wind streaming from our Sun. Just as solar storms on Earth push the northern lights to more southern latitudes, Jupiter’s auroras are also affected by our Sun’s activity. In September 2019, a massive, high-density solar stream buffeted Jupiter’s magnetosphere, briefly revealing — as the auroral oval moved toward Jupiter’s equator — a faint but distinct signature associated with Callisto. This discovery finally confirms that all four Galilean moons leave their mark on Jupiter’s atmosphere, and that Callisto’s footprints are sustained much like those of its siblings, completing the family portrait of the Galilean moon auroral signatures.
An international team of scientists led by Jonas Rabia of the Institut de Recherche en Astrophysique et Planétologie (IRAP), CNRS, CNES, in Toulouse, France, published their paper on the discovery, “In situ and remote observations of the ultraviolet footprint of the moon Callisto by the Juno spacecraft,” in the journal Nature Communications on Sept. 1, 2025.
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Last Updated Sep 02, 2025 Related Terms
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By NASA
NASA/Kim Shiflett NASA astronauts Christina Koch, Artemis II mission specialist, and Victor Glover, Artemis II pilot, walk on the crew access arm of the mobile launcher in the Vehicle Assembly Building at NASA’s Kennedy Space Center in Florida on Tuesday, Aug. 12, 2025.
On Aug. 11 and 12, teams with the agency’s Exploration Ground Systems Program along with NASA astronauts Reid Wiseman, Victor Glover, and Christina Koch, and CSA (Canadian Space Agency) astronaut Jeremy Hansen, practiced launch day operations if launch occurs at night. They simulated putting their spacesuits on and driving to the launch pad as well as emergency procedures they would use in the unlikely event of an emergency during the launch countdown requiring them to evacuate the launch pad.
Through the Artemis campaign, NASA will send astronauts to explore the Moon for scientific discovery, economic benefits, and to build the foundation for the first crewed missions to Mars.
Image credit: NASA/Kim Shiflett
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By NASA
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NASA’s Black Marble: Stories from the Night Sky
Earth (ESD) Earth Explore Explore Earth Home Air Quality Climate Change Freshwater Life on Earth Severe Storms Snow and Ice The Global Ocean Science at Work Earth Science at Work Technology and Innovation Powering Business Multimedia Image Collections Videos Data For Researchers About Us Viewed from space, Earth at night tells endless stories. Using satellite data, we can track population growth, natural disaster damage, cultural celebrations, and even space weather. Studying these glowing patterns helps us understand human activity, respond to disasters, and witness a changing world.
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Last Updated Aug 04, 2025 Related Terms
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By NASA
As the Sun approaches the most active part of its eleven-year magnetic cycle this summer, NASA volunteers have been watching it closely. Now they’ve spotted a new trend in solar behavior that will have you reaching for your suntan lotion. It’s all about something called a “Type II” solar radio burst:
“Type II solar radio bursts are not commonly detected in the frequency range between 15 to 30 megahertz,” said Prof. Chuck Higgins, Co-founder of Radio JOVE. “Recently, we’re seeing many of them in that range.”
Let’s unpack that. Our Sun often sprays powerful blasts of radio waves into space. Heliophysicists classify these radio bursts into five different types depending on how the frequency of the radio waves drifts over time. “Type II” solar radio bursts seem to come from solar flares and enormous squirts of hot plasma called coronal mass ejections.
Now, Thomas Freeman, an undergraduate student at Middle Tennessee State University, and other volunteers working on NASA’s Radio JOVE project have observed something interesting about these Type II bursts: they are now showing up at lower frequencies—somewhere in between FM and AM radio.
What does it mean? It means our star is full of surprises! These Radio JOVE observations of the Sun’s radio emissions during solar maximum can be used to extend our knowledge of solar emissions to lower frequencies and, therefore, to distances farther from the Sun.
Radio JOVE is a NASA partner citizen science project in which participants assemble and operate radio astronomy telescopes to gather and contribute data to support scientific studies. Radio JOVE collaborated with SunRISE Ground Radio Lab, organized teams of high school students to observe the Sun, and recently published a paper on these Type II solar radio bursts. Learn more and get involved!
A Type II solar radio burst on April 23rd, 2024, seen as the gently sloping yellow band drifting from 17:49 to 18:02 UTC in the 15-30 MHz radio frequency-time spectrogram. Credit: Tom Ashcraft, Lamy, NM Share
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Last Updated Jul 23, 2025 Related Terms
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