Nov. 15, 2022: On Nov. 3rd, 2022, sky watchers in Sweden and Norway watched a strange blue aurora snake across the night sky. Its color and motion seemed to defy the normal laws of aurora physics. Indeed, it was not an aurora. Experts quickly realized that the display coincided with the launch of an ICBM from a Russian submarine beneath the White Sea.
It wasn’t the first time blue clouds have appeared. On Dec. 9, 2009, a Russian rocket caused a worldwide sensation when it created a blue spiral over Norway. “Blue auroras” appeared again on Oct. 26, 2017, following another Russian battle drill:
The blue exhaust of a Russian rocket on Oct. 26, 2017. Credit: Alexey Yakovlev of Strezhevoy, Russia
Over the years, Arctic sky watchers have seen many of these blue clouds, with explanations ranging from auroras to aliens to wormholes in space. In fact, rockets are the most likely explanation. Common threads seem to be the involvement of Bulava and Topol missiles, and the use of solid propellant ascent motors.
A paper published in 2016, “Exceptional optical phenomena observed during the operation of Russian launchers,” explains how such rockets might produce blue lights:
“A major combustion product of the solid fuel is aluminum oxide Al2O3 (~40% by mass),” the authors write. “At high temperatures, the formation of aluminum monoxide, AlO, also occurs. AlO exists in a gaseous state. Resonant scattering of sunlight by these molecules causes the luminescence in the wavelength region 4374–5424 Ǻ, which corresponds to the turquoise color of the gas-dust trail of the rocket.”
Mystery solved? Probably. But that doesn’t mean we don’t want to investigate further. Arctic sky watchers, if you see any future “blue auroras,” submit your photos here.