Citizen scientist knowledge assist uncover the mysteries of a blue low-latitude aurora

Colourful auroras appeared round Japan’s Honshu and Hokkaido islands on Might 11, 2024, sparked by an intense magnetic storm. Often, auroras noticed at low latitudes seem purple as a result of emission of oxygen atoms. However on today, a salmon pink aurora was noticed all through the night time, whereas an unusually tall, blue-dominant aurora appeared shortly earlier than midnight.

Smartphone movies and novice images captured the occasion, enabling scientists to mix public knowledge with their very own analysis and examine the phenomenon.

In a brand new examine, researchers analyzed the movies and pictures of the blue-dominant aurora to estimate the realm of the phenomenon and confirmed the estimates with spectrophotometers.

Printed within the journal Earth, Planets and Area, the analysis was led by Sota Nanjo, a postdoctoral researcher on the Swedish Institute of Area Physics in Sweden, and Professor Kazuo Shiokawa from the Institute for Area-Earth Environmental Analysis (ISEE) at Nagoya College in Japan.

Nanjo and Shiokawa’s investigation supplied the primary visualization of the spatial construction of blue-dominant auroras throughout a storm. The researchers discovered that the auroras had longitudinal constructions that have been aligned with magnetic area traces, the primary time that they had been recognized in a low-latitude, blue-dominant aurora.

In addition they discovered that the aurora spanned about 1,200 km in longitude, consisted of three separate constructions, and ranged in altitude from 400–900 km.

Nanjo and Shiokawa’s findings could change our understanding of blue auroras. The ring present, a donut-shaped area of charged particles encircling Earth, is believed to be the supply of energetic impartial atoms (ENAs) that produce low-latitude auroras, together with the purple aurora. Based on this mannequin, the storm probably energized the ENAs, creating a colourful show of sunshine.

Nevertheless, the group’s discoveries can’t simply be defined by this mechanism. As Shiokawa explains, “On this examine, a construction of a number of hundred kilometers was discovered within the blue-dominant aurora within the longitudinal path, which is tough to interpret by ENA exercise solely. As well as, ENAs are unlikely to create auroral constructions aligned with magnetic area traces, as noticed on this examine.”

One other risk was that the aurora was because of resonant scattering of nitrogen molecular ions brought on by daylight irradiation. Nevertheless, the group’s analysis suggests {that a} totally different course of occurred, as daylight solely reached right down to 700 km, not the 400 km noticed by the researchers.

As a substitute, their outcomes could point out the intriguing risk of an unidentified course of. “Our findings recommend that nitrogen molecular ions could have accelerated upward by some mechanism and have been chargeable for the formation of the blue-dominant aurora,” Shiokawa stated.

“Up to now, it isn’t effectively understood how nitrogen molecular ions with massive molecular weight can exist at such excessive altitudes,” he continued. “Such ions will not be simply in a position to exist for lengthy intervals of time because of their heavy mass and brief dissociative-recombination time intervals; nonetheless, they’re noticed at excessive altitudes. The method is shrouded in thriller.”

General, repeated observations of blue-dominant auroras, such because the one noticed in Japan, could present clues to grasp the precept behind how nitrogen could be discovered at these altitudes.

As the method of nitrogen molecular ion outflow into the magnetosphere is necessary in every little thing from understanding geomagnetic storms and the radiation setting in area, these findings might assist us perceive the processes that happen lots of of kilometers above us.