A special spot up Northern Minnesota's Gunflint Trail has night skies that rank among the darkest on Earth.
The End of Trail Campground, at the end of the Gunflint in Cook County, has skies that rank a one on the Bortle Scale.
"It's as dark as the darkest places in the world," said photographer Bryan Hansel.
The Bortle scale was created by an astronomer, John Bortle, in 2001. It ranks the darkness of locations on a scale of one to nine; nine being inner city skies, one being the darkest.
"So, if you turned off the lights everywhere in the world, they would have a Bortle one," said Hansel, "In the lower 48 [states] there's very few of them and... this is the only one in Minnesota."
The dark skies draw in students to Hansel's night sky photography workshop. He's been teaching them in Cook County for five or six years, and says they fill up fast, often with a waiting list.
"The darker it [the sky] is in photography, the more stars you get in your picture," said Hansel, "So, if you have less light pollution you simply see a lot more stars, airglow, different sky phenomenons."
Hansel advertises the dark location on his workshop website. He says people from all over the world come to Minnesota to take the class.
"A guy from Tanzania came in once. I've had people fly in from India, so we get people from around the world coming up here," Hansel said.
Hansel attributes the popularity of night sky photography to advances in equipment that allow less expensive cameras to take better pictures at night.
"The equipment is so good now, that someone with an average level camera can come away with great night sky pictures. Where as ten years ago, that wasn't the case, so just because the equipment is capable of doing that now, people want to get out and shoot the night sky."
There's no official entity that ranks locations according to the Bortle scale. Rather each number on the scale corresponds with a set of guidelines which define that ranking based on what you can see in the sky at that level of darkness. The end of the Gunflint meets all the requirements for a Bortle one.
You can find the Bortle Scale rankings here.