Neptune’s auroras have been captured in unprecedented detail by NASA’s James Webb Space Telescope. These luminous phenomena, first faintly detected in ultraviolet light during Voyager 2’s 1989 flyby, have now been observed in infrared light, providing direct evidence of their presence. NASA released these images recently, and the findings were published in Nature Astronomy.
Auroras are created when electrically charged particles from space enter a planet’s atmosphere and collide with atmospheric molecules. This interaction results in a series of reactions that emit light. On Earth, this process predominantly occurs near the polar regions, leading to the creation of the breathtaking northern and southern lights.
While scientists have extensively studied the auroras of Saturn and Jupiter, investigating Neptune—being the farthest planet from the sun—has posed greater challenges. “Neptune has always been elusive,” commented James O’Donoghue, a planetary scientist at the University of Reading, and co-author of the study. Its auroras, observed only once by Voyager, have since been a subject of interest.
Unlike Earth, Neptune’s auroras occur near the mid-latitudes due to the unique attributes of its magnetic field, which influences their geographical span, explained O’Donoghue. Over thirty years after Voyager 2’s encounter, Neptune’s auroras were once again observed with the Webb telescope, marking “the first robust detection,” as highlighted by Heidi Hammel of the Association of Universities for Research in Astronomy.
In addition to unveiling the auroras, researchers discovered that Neptune’s atmosphere has cooled significantly since the 1980s. This cooling could be linked to the dimming of its auroras over recent decades.