{"id":331139,"date":"2026-03-06T00:55:12","date_gmt":"2026-03-06T00:55:12","guid":{"rendered":"https:\/\/www.newsbeep.com\/ie\/331139\/"},"modified":"2026-03-06T00:55:12","modified_gmt":"2026-03-06T00:55:12","slug":"webb-captures-ios-and-europas-auroral-footprints-in-jupiters-atmosphere","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/ie\/331139\/","title":{"rendered":"Webb Captures Io\u2019s and Europa\u2019s Auroral Footprints in Jupiter\u2019s Atmosphere"},"content":{"rendered":"

The NASA\/ESA\/CSA James Webb Space Telescope conducted a clockwise scan around the entire limb of Jupiter, chasing aurora<\/a> as it rotated into view. This dynamic phenomenon is a result of charged particles traveling down magnetic field lines, crashing into the planet\u2019s ionosphere and causing it to glow. During the scan, Webb\u2019s Near-Infrared Spectrograph (NIRSpec) captured an extraordinary aspect of Jupiter\u2019s aurora, known as auroral footprints<\/a>, which are bright emission patterns produced as a result of the interaction between Jupiter\u2019s Galilean moons and the space environment surrounding the giant planet. Using the NIRSpec data, planetary scientists measured the physical properties of the auroral footprints of Jupiter\u2019s two innermost Galilean moons, Io and Europa, including the local temperature and ionospheric density, in the near-infrared. They discovered a never-seen-before low temperature structure centered on Io\u2019s bright spot of emission, possessing extremely high densities; this is likely driven by extreme changes in the flow of electrons crashing into the upper atmosphere.<\/p>\n

\"Webb<\/a><\/p>\n

Webb captured the auroral footprints of Io and Europa, providing spectral measurements for the first time, and revealing extreme changes in the physical properties within Io\u2019s auroral footprint that are likely linked to the electrons crashing into the top of Jupiter\u2019s atmosphere. Image credit: NASA \/ ESA \/ CSA \/ Webb \/ NIRCam \/ Jupiter ERS Team \/ Judy Schmidt \/ Katie L. Knowles, Northumbria University.<\/p>\n

\u201cThese emissions have been measured before at ultraviolet and infrared wavelengths, but only how brightly they shine,\u201d said lead author Katie Knowles, a Ph.D. student at Northumbria University.<\/p>\n

\u201cFor the first time, we\u2019ve now been able to describe the physical properties of the auroral footprints \u2014 the temperature of the upper atmosphere and the ion density, which has never been reported on before.\u201d<\/p>\n

Unlike Earth\u2019s northern lights, which are primarily driven by the solar wind, Jupiter\u2019s aurora includes the impact of its four large Galilean moons \u2014 Io, Europa, Ganymede, and Callisto \u2014 which create their own \u2018mini aurora\u2019 on the planet.<\/p>\n

Jupiter\u2019s powerful magnetic field rotates approximately once every 10 hours along with the planet itself, carrying charged particles with it.<\/p>\n

But its moons orbit much more slowly \u2014 Io, the innermost moon, takes around 42.5 hours to complete one orbit.<\/p>\n

\u201cThe moons constantly interact with the magnetic field and plasma surrounding the planet, and that interaction leads to highly energetic particles travelling down magnetic field lines and then crashing into the planet\u2019s atmosphere, creating the auroral footprints that map to where the moons orbit around Jupiter,\u201d Knowles said.<\/p>\n

\u201cJupiter\u2019s aurora is the most powerful and constant of any aurora in the Solar System.\u201d<\/p>\n

\u201cWhat we\u2019re seeing with Webb gives us an unprecedented window into how Jupiter\u2019s moons directly affect the top of the planet\u2019s atmosphere.\u201d<\/p>\n

During a 22-hour window of observation time which took place in September 2023, Webb scanned around the edge of Jupiter, chasing the northern lights as they rotated into view.<\/p>\n

It was during this observation that they also happened to capture the auroral footprints.<\/p>\n

However, the footprints created by Io and Europa, did not have the characteristics expected from Jupiter\u2019s main aurora, which is relatively hot and contains a lot of material.<\/p>\n

Instead, in one snapshot, they discovered a cold spot within Io\u2019s auroral footprint that registered temperatures much lower than expected with extraordinarily high densities.<\/p>\n

Io is the most volcanically active body in our Solar System, with its volcanoes ejecting about 1,000 kilograms of material into space every second, feeding the dense plasma surrounding Jupiter.<\/p>\n

This material becomes ionized and forms a doughnut-shaped cloud around Jupiter called the Io plasma torus.<\/p>\n

As Io moves through this environment, it generates powerful electrical currents that create the brightest spots in Jupiter\u2019s aurora.<\/p>\n

The researchers found that these auroral footprints contain trihydrogen cation densities three times higher than those found in Jupiter\u2019s main aurora, with some regions showing density variations of up to 45 times within the same small area.<\/p>\n

\u201cWe found extreme variability in both temperature and density within Io\u2019s auroral footprint that happened on the timescale of minutes,\u201d Knowles said.<\/p>\n

\u201cThis tells us that the flow of high-energy electrons crashing into Jupiter\u2019s atmosphere is changing incredibly rapidly.\u201d<\/p>\n

\u201cThe cold spot registered temperatures of just 538 K (265 degrees Celsius or 509 degrees Fahrenheit) compared to 766 K (493 degrees Celsius or 919 degrees Fahrenheit) in the rest of Jupiter\u2019s aurora.\u201d<\/p>\n

\u201cThe cold spot also contained material three times denser than Jupiter\u2019s main aurora.\u201d<\/p>\n

The findings could extend far beyond Jupiter and open questions about other planetary systems.<\/p>\n

Saturn\u2019s moon, Enceladus, also creates an auroral footprint on the planet, and scientists wonder whether similar phenomena occur there.<\/p>\n

\u201cThis work opens up entirely new ways of studying not just Jupiter and its other Galilean moons, but potentially other giant planets and their moon systems,\u201d Knowles said.<\/p>\n

\u201cWe\u2019re seeing Jupiter\u2019s atmosphere respond to its moons in real-time, which gives us insights into processes that occur throughout our Solar System and perhaps further afar.\u201d<\/p>\n

\u201cWe only saw this phenomenon in one of our five snapshots which leave us with questions. How often does this occur? Does it switch on and off? How does it change with different conditions?\u201d<\/p>\n

The study<\/a> appears in the journal Geophysical Research Letters.<\/p>\n

_____<\/p>\n

Katie L. Knowles et al. 2026. Short-Term Variability of Jupiter\u2019s Satellite Footprints as Spotted by JWST. Geophysical Research Letters 53 (5): e2025GL118553; doi: 10.1029\/2025GL118553<\/p>\n","protected":false},"excerpt":{"rendered":"The NASA\/ESA\/CSA James Webb Space Telescope conducted a clockwise scan around the entire limb of Jupiter, chasing aurora…\n","protected":false},"author":2,"featured_media":331140,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[10803,4286,152679,10804,10805,30030,152680,25260,61,25915,25261,37160,60,3626,35968,91,23190,152681,82,3630,5623],"class_list":{"0":"post-331139","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-science","8":"tag-atmosphere","9":"tag-aurora","10":"tag-auroral-footprint","11":"tag-csa","12":"tag-esa","13":"tag-europa","14":"tag-galilean-moons","15":"tag-gas-giant","16":"tag-ie","17":"tag-io","18":"tag-ionosphere","19":"tag-ir","20":"tag-ireland","21":"tag-jupiter","22":"tag-magnetic-field","23":"tag-nasa","24":"tag-planet","25":"tag-satellite-footprint","26":"tag-science","27":"tag-solar-system","28":"tag-webb"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts\/331139","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/comments?post=331139"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts\/331139\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/media\/331140"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/media?parent=331139"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/categories?post=331139"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/tags?post=331139"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}