A rare natural electrical phenomenon was recently captured in images of the night sky over Iceland’s Kerid Crater.
Photographer Jeff Dai, a resident of China who is currently traveling in Iceland, observed an unusual rippling motion within the green bands of the aurora borealis on January 16, 2024.
The phenomenon sparked his curiosity, and Dai went for his camera.
“I captured this rare image of ‘aurora curls’,” Dai said. “They rippled across the zenith for several minutes.”
Dai’s amazing imagery was subsequently featured at spaceweather.com, the long-running online provider of information about the Sun-Earth environment.
Reaching out to Xing-Yu Li, a scientist with Peking University’s Institute of Space Physics and Applied Technology, Dai learned that the phenomenon he managed to photograph occurs when the Earth’s magnetic field vibrates, the wavelengths of which become visible as “ripples” during auroral displays like the one he photographed earlier this month.
The photographs reveal a rare physical manifestation of the phenomenon, which is normally only viewed in data collected by instrumentation used to monitor our planet’s magnetosphere.
“It is a very rare sighting, indeed,” remarked Dr. Tony Phillips, who runs spaceweather.com.
Precisely what causes the appearance of these sinewave-like structures remains in debate among experts, although one theory involves a phenomenon in fluid dynamics where ultra-low frequency waves could be inducing what is called shear flow.
“These curls are fine structures in the poleward boundary of multiple arcs formed by longitudinal-arranged field-aligned current pairs,” Dai wrote in an Instagram post featuring a short video of the phenomenon he captured over Iceland this month.
Dai added that it appears the visible auroral undulations were triggered “by Kelvin-Helmholtz Waves.”
“The view was captured when the aurora appears in the zenith,” Dai wrote.
Dai’s remarkable image of aurora curls over Iceland is only one of his rich night sky offerings. The youngest member of The World at Night project and a National Coordinator at Astronomers Without Borders, Dai’s passion for astrophotography began during a camping trip in 2011, which led to his long-term Silk Road at Night project.
His photography has been featured in several international media outlets, and he is also an advocate for preserving natural skies in China with the International Dark Sky Association.