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aristarchus [soylentnews.org] writes:

Aurorae on Jupiter. Very interesting. Article at Phys.org [phys.org].

New results from the Ultraviolet Spectrograph instrument on NASA's Juno mission reveal for the first time the birth of auroral dawn storms—the early morning brightening unique to Jupiter's spectacular aurorae. These immense, transient displays of light occur at both Jovian poles and had previously been observed only by ground-based and Earth-orbiting observatories, notably NASA's Hubble Space Telescope. Results of this study were published March 16 in the journal AGU Advances.

First discovered by Hubble's Faint Object Camera in 1994, dawn storms consist of short-lived but intense brightening and broadening of Jupiter's main auroral oval—an oblong curtain of light that surrounds both poles—near where the atmosphere emerges from darkness in the early morning region. Before Juno, observations of Jovian ultraviolet aurora had offered only side views, hiding everything happening on the nightside of the planet.

"Observing Jupiter's aurora from Earth does not allow you to see beyond the limb, into the nightside of Jupiter's poles. Explorations by other spacecraft—Voyager, Galileo, Cassini—happened from relatively large distances and did not fly over the poles, so they could not see the complete picture," said Bertrand Bonfond, a researcher from the University of Liège in Belgium and lead author of the study. "That's why the Juno data is a real game changer, allowing us a better understanding what is happening on the nightside, where the dawn storms are born."

Dawn Storms! Hmm, not quite what they were expecting! But it is light rather than darkness.

Original Submission