A huge floating ice disk has been rotating in the Presumpscot River in Westbrook, Maine.
Tina Radel, a city employee, told WCSH that birds have been sitting on the disk as it slowly turns counterclockwise. She called the disk a natural phenomenon.
Rob Mitchell, who owns a nearby office building, spotted the alien-looking disk Monday morning and immediately notified the city of Westbrook, just outside Portland. The formation was widely shared on social media and has drawn comparisons to an alien spacecraft, a carousel and the moon.
"It looks like the moon has landed in Westbrook!" the city said in a post on Facebook.
“It kind of looks like a crop circle,” Doug Bertlesman, who works in Westbrook, told The Portland Press Herald. "It's pretty wild to look at."
When water channels through a winding river, there are many eddies, or circular flows of water embedded in the general flow, according to NBC10 Boston meteorologist Tim Kelley.
Usually these eddies are not noticed by spectators, but he said those who frequent rivers on a kayak are quite familiar with them.
"The flow near the center of the ice mass is nearly stationary," Kelley said, "allowing the water to freeze more readily, while water moves faster around the edges, generating the spin."
The ice disk, which is an estimated 100 yards across, is in a part of the river between the end of Ash Street on one side and near Saccarappa Falls behind the Dana Court parking garage on the other.