Pulsating auroras are Blakley's favorite: "The best way to describe a pulsating aurora is to imagine the sky as a large checker board," he says. "As the pulsating begins, black squares on the board would illuminate as a green aurora. Then, in an instant, all the black squares lose their illumination and the red squares on the imaginary checkerboard immediately glow green."
In this case, however, the green was pink. Pink auroras appear when solar wind particles penetrate unusually deep in Earth's atmosphere, striking nitrogen molecules less than 100 km above our planet's surface. A crack in Earth's magnetic field on Oct. 3rd let the particles reach that level.
Pulsating auroras are so mysterious, NASA keeps launching rockets into them to learn what makes them tick. In 2018, researchers led by S. Kasahara of the University of Tokyo conclusively linked pulsating auroras to "chorus waves" in Earth's magnetosphere. Their findings explain everything -- except the shape of the 'squares' and why they blink so quickly. Keep launching rockets, NASA.