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Green blotches show where auroras light up Neptune\u2019s skies<\/p>\n
NASA, ESA, CSA, STScI, Heidi Hammel (AURA), Henrik Melin (Northumbria University), Leigh Fletcher (University of Leicester), Stefanie Milam (NASA-GSFC)<\/p>\n<\/div>\n<\/figcaption><\/figure>\n<\/p>\n
For the first time, researchers have spotted infrared auroras swirling in Neptune\u2019s atmosphere, verifying decades of scientific speculation.<\/p>\n
When NASA\u2019s Voyager 2 mission flew by Neptune in 1989, it found tantalising hints of aurora activity in the ice giant\u2019s clouds. However, scientists were unable to verify the phenomenon at the time, as existing instruments were too weak. Now, the James Webb Space Telescope (JWST) has finally provided the power to detect them.<\/p>\n
\u201cThis was really a fulfillment of years\u2019 worth of anticipation,\u201d says Heidi Hammel at the Association of Universities for Research in Astronomy in Washington DC.<\/p>\n
Hammel and her colleagues used JWST\u2019s NIRSpec, a powerful infrared imaging tool, to capture spectroscopic images of Neptune and analyse the different wavelengths of light emitted by the planet. In 2023, researchers used the instrument to detect infrared auroras on Uranus<\/span>. This time, it found them on Neptune as well.<\/p>\n The images also allowed Hammel and her team to begin constructing a map of Neptune\u2019s magnetic field. This is particularly exciting as the planet is known to have some of the most unusual magnetic poles in the solar system.<\/p>\n <\/p>\n Unlike Earth, Jupiter or Saturn, Neptune\u2019s magnetic poles aren\u2019t centered at its rotational poles. Instead, \u201cthey\u2019re offset by almost half the planet\u2019s radius\u201d, says Hammel. As a result, its auroras appear as irregular blobs much closer to its equator, over roughly the region where South America sits on a globe model of Earth.<\/p>\n In addition to detecting auroras, the JWST observations indicated that Neptune\u2019s ionosphere \u2013 the layer of charged particles blanketing some planets \u2013 is cooling down. It is now, on average, about 10 per cent colder than when Voyager 2 passed by 34 years ago. Similar changes have been detected on Uranus.<\/p>\n While the authors of the new study aren\u2019t sure why this cooling occurred, they hope their next JWST observation period, scheduled for 2026, will offer more clues.<\/p>\n Topics:<\/p>\n<\/section><\/div>\n