Fairbanks has reached a major summer milepost: it won't be truly dark again for more than two months.
The Interior Alaska city has entered its annual string of 72 days where the sun just barely dips below the horizon at night, leaving a lingering glow known as civil twilight.
Civil twilight means the sun travels no more than 6 degrees below the horizon, said Brian Brettschneider, a climate researcher at the University of Alaska Fairbanks International Arctic Research Center.
"It's usable twilight," Brettschneider said, meaning people can take part in outdoor activities without needing additional light.
Civil twilight began Tuesday at 1:53 a.m., according to the U.S. Naval Observatory. The city won't see civil twilight end again until July 27 at 1:40 a.m.
Sitting about 100 miles south of the Arctic Circle, Fairbanks doesn't technically get 24 hours of sunlight, Brettschneider said, but civil twilight can make it feel like it does.
On June 21, the longest day of summer, the sun sets in Fairbanks at 12:47 a.m., and rises at 2:59 a.m.