{"id":191154,"date":"2025-03-26T20:00:00","date_gmt":"2025-03-26T10:00:00","guid":{"rendered":"https:\/\/science.nasa.gov\/missions\/webb\/nasas-webb-captures-neptunes-auroras-for-first-time\/"},"modified":"2025-03-26T20:00:00","modified_gmt":"2025-03-26T10:00:00","slug":"nasas-webb-captures-neptunes-auroras-for-first-time","status":"publish","type":"post","link":"https:\/\/www.vibewire.com.au\/?p=191154","title":{"rendered":"NASA\u2019s Webb Captures Neptune\u2019s Auroras For First Time"},"content":{"rendered":"
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6 Min Read<\/div>\n

\n\t\t\t\t\t\t\t\tNASA\u2019s Webb Captures Neptune\u2019s Auroras For First Time\t\t\t\t\t\t\t<\/h1>\n<\/p>\n<\/div>\n<\/div>\n
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\"A<\/figure>\n<\/p>\n<\/div>\n<\/div>\n<\/div>\n
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At the left, an enhanced-color image of Neptune from NASA\u2019s Hubble Space Telescope. At the right, that image is combined with data from NASA\u2019s James Webb Space Telescope.<\/figcaption><\/div>\n<\/p>\n<\/div>\n
\n\t\t\t\t\t\t\tCredits: <\/span>
\n\t\t\t\t\t\t\tNASA, ESA, CSA, STScI, Heidi Hammel (AURA), Henrik Melin (Northumbria University), Leigh Fletcher (University of Leicester), Stefanie Milam (NASA-GSFC)<\/span>\n\t\t\t\t\t\t<\/div>\n<\/figcaption><\/div>\n<\/p>\n<\/div>\n<\/div>\n

Long-sought auroral glow finally emerges under Webb\u2019s powerful gaze<\/strong><\/em><\/p>\n

For the first time, NASA\u2019s James Webb Space Telescope has captured bright auroral activity on Neptune. Auroras occur when energetic particles, often originating from the Sun, become trapped in a planet\u2019s magnetic field and eventually strike the upper atmosphere. The energy released during these collisions creates the signature glow.<\/p>\n

In the past, astronomers have seen tantalizing hints of auroral activity on Neptune, for example, in the flyby of NASA\u2019s Voyager 2 in 1989. However, imaging and confirming the auroras on Neptune has long evaded astronomers despite successful detections on Jupiter, Saturn, and Uranus. Neptune was the missing piece of the puzzle when it came to detecting auroras on the giant planets of our solar system.<\/p>\n

\u201cTurns out, actually imaging the auroral activity on Neptune was only possible with Webb\u2019s near-infrared sensitivity,\u201d said lead author\u00a0Henrik Melin of Northumbria University,\u00a0who conducted the research while at the University of Leicester. \u201cIt was so stunning to not just see the auroras, but the detail and clarity of the signature really shocked me.\u201d<\/p>\n

The data was obtained in June 2023 using Webb\u2019s Near-Infrared Spectrograph<\/a>. In addition to the image of the planet, astronomers obtained a spectrum<\/a> to characterize the composition and measure the temperature of the planet\u2019s upper atmosphere (the ionosphere). For the first time, they found an extremely prominent emission line<\/a> signifying the presence of the trihydrogen cation (H3<\/sub>+<\/sup>), which can be created in auroras. In the Webb images of Neptune, the glowing aurora appears as splotches represented in cyan.<\/p>\n

Image A:
Neptune\u2019s Auroras \u2013 Hubble and Webb<\/h2>\n
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\"A<\/a><\/figure>
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At the left, an enhanced-color image of Neptune from NASA\u2019s Hubble Space Telescope. At the right, that image is combined with data from NASA\u2019s James Webb Space Telescope. The cyan splotches, which represent auroral activity, and white clouds, are data from Webb\u2019s Near-Infrared Spectrograph (NIRSpec), overlayed on top of the full image of the planet from Hubble\u2019s Wide Field Camera 3.<\/div>\n
NASA, ESA, CSA, STScI, Heidi Hammel (AURA), Henrik Melin (Northumbria University), Leigh Fletcher (University of Leicester), Stefanie Milam (NASA-GSFC)<\/div>\n<\/figcaption><\/div>\n<\/div>\n<\/div>\n

\u201cH3<\/sub>+<\/sup> has a been a clear signifier on all the gas giants \u2014 Jupiter, Saturn, and Uranus \u2014 of auroral activity, and we expected to see the same on Neptune as we investigated the planet over the years with the best ground-based facilities available,\u201d explained Heidi Hammel of the Association of Universities for Research in Astronomy, Webb interdisciplinary scientist and leader of the Guaranteed Time Observation program for the Solar System in which the data were obtained. \u201cOnly with a machine like Webb have we finally gotten that confirmation.\u201d<\/p>\n

The auroral activity seen on Neptune is also noticeably different from what we are accustomed to seeing here on Earth, or even Jupiter<\/a> or Saturn<\/a>. Instead of being confined to the planet\u2019s northern and southern poles, Neptune\u2019s auroras are located at the planet\u2019s geographic mid-latitudes \u2014 think where South America is located on Earth.<\/p>\n

This is due to the strange nature of Neptune\u2019s magnetic field<\/a>, originally discovered by Voyager 2 in 1989<\/a> which is tilted by 47 degrees from the planet\u2019s rotation axis. Since auroral activity is based where the magnetic fields converge into the planet\u2019s atmosphere, Neptune\u2019s auroras are far from\u00a0its rotational\u00a0poles.<\/p>\n

The ground-breaking detection of Neptune\u2019s auroras will help us understand how Neptune\u2019s magnetic field interacts with particles that stream out from the Sun to the distant reaches of our solar system, a totally new window in ice giant atmospheric science.<\/p>\n

From the Webb observations, the team also measured the temperature of the top of Neptune\u2019s atmosphere for the first time since Voyager 2\u2019s flyby. The results hint at why Neptune\u2019s auroras remained hidden from astronomers for so long.<\/p>\n

\u201cI was astonished \u2014 Neptune\u2019s upper atmosphere has cooled by several hundreds of degrees,\u201d Melin said. \u201cIn fact, the temperature in 2023 was just over half of that in 1989.\u201d\u00a0<\/p>\n

Through the years, astronomers have predicted the intensity of Neptune\u2019s auroras based on the temperature recorded by Voyager 2. A substantially colder temperature would result in much fainter auroras. This cold temperature is likely the reason that Neptune\u2019s auroras have remained undetected for so long. The dramatic cooling also suggests that this region of the atmosphere can change greatly even though the planet sits over 30 times farther from the Sun compared to Earth.
Equipped with these new findings, astronomers now hope to study Neptune with Webb over a full solar cycle, an 11-year period of activity driven by the Sun\u2019s magnetic field. Results could provide insights into the origin of Neptune\u2019s bizarre magnetic field, and even explain why it\u2019s so tilted.<\/p>\n

\u201cAs we look ahead and dream of future missions to Uranus and Neptune, we now know how important it will be to have instruments tuned to the wavelengths of infrared light to continue to study the auroras,\u201d added Leigh Fletcher of Leicester University, co-author on the paper. \u201cThis observatory has finally opened the window onto this last, previously hidden ionosphere of the giant planets.\u201d<\/p>\n

These observations, led by Fletcher, were taken as part of Hammel\u2019s Guaranteed Time Observation program 1249<\/a>. The team\u2019s results have been published in Nature Astronomy<\/em><\/a>.<\/p>\n

The James Webb Space Telescope is the world\u2019s premier space science observatory. Webb is solving mysteries in our solar system, looking beyond to distant worlds around other stars, and probing the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and CSA (Canadian Space Agency).<\/p>\n<\/p>\n

Downloads<\/h2>\n

Click any image to open a larger version.<\/strong><\/p>\n

View\/Download all image products at all resolutions<\/a><\/strong> for this article from the Space Telescope Science Institute.<\/p>\n

Read the research results <\/strong>published in Nature Astronomy<\/em><\/a>.<\/p>\n

Media Contacts<\/h2>\n

Laura\u00a0Betz<\/strong>\u00a0\u2013\u00a0laura.e.betz@nasa.gov<\/a>
NASA\u2019s Goddard Space Flight Center<\/a>, Greenbelt, Md.<\/p>\n

Hannah Braun- <\/strong>hbraun@stsci.edu<\/a>
<\/strong>Space Telescope Science Institute, Baltimore, Maryland<\/p>\n

Christine Pulliam<\/strong> \u2013 cpulliam@stsci.edu<\/a>
Space Telescope Science Institute<\/a>, Baltimore, Md.<\/p>\n

Science<\/h2>\n

Henrik Melin (Northumbria University)<\/p>\n