As the aurora borealis danced across the night sky on October 10, social media lit up with posts from dazzled Delaware residents. After all, our state isn’t typically a hot spot for viewing the northern lights.
According to Bennett Maruca, an associate professor of physics and astronomy at the University of Delaware, we owe the spectacle to a significant solar flare. “Very frequently, when you have a big solar flare on the sun, you have an extra blast of plasma that comes with it,” he explains. These coronal mass ejections bring electrically charged particles.
Fortunately, Earth’s magnetic field keeps the lethal radiation from stripping away our protective atmosphere and frying us all, Maruca notes. While some particles make it through to the atmosphere, the magnetic field generally funnels them to the area of the poles, where they react with other elements, like oxygen, to create otherworldly light displays.
The most intense solar activity can push even more particles through space, lending visibility farther from the poles. “The degree to which it glows, well, that depends on how much solar wind you have driving it,” Maruca says.
One famous 1859 solar storm was so intense that people reportedly awoke during the night to what they were sure was a fire raging nearby. It was a magnificent display, although telegraph lines went haywire. (A similar event now could wreak havoc with modern electrical systems.) Storms that size are rare, but the sun does go through active phases—and we’re in one now.
Delaware could have experienced a similar light display last spring, Maruca says, but cloudy weather ruined the show.
