WESTBROOK, Maine — A spinning circle of ice that has formed in the Presumpscot River has captivated the world.

Thousands of people are mesmerized by the whirling wonder in Westbrook on social media.

RELATED: Giant ice disk floating, rotating in Westbrook's Presumpscot River

“It’s the moon in the river,” one person commented. “Pretty cool!”

Others hinted that it might be the work of aliens, even posting GIFs from the award-winning movie E.T.

“I have not seen anything like this,” city councilor Gary Rairdon said. “I’ve lived probably 52 years of my life in Westbrook.”

But how the heck did it form?

“The river has different depths,” NEWS CENTER Maine Meteorologist Ryan Breton said. “On the right side where there isn’t any ice it’s a faster current. On the left side, where the ice started to form it’s a little shallower, and that ice started to form into a circle that completely changed around the current of the entire river.”

Westbrook 'ice disk' explainer
NCM

A combination of fast current in deep water and slow current in shallow water with water-freezing temperatures creates ice, which forms in the shallows, according to Breton.

The currents create an eddy, ice rotates and builds to form a disk.

“It’s almost like Mother Nature’s merry-go-round,” Rairdon said.

The formation located near Saccarappa Falls was first shared by the city with a drone photo on its Facebook page. 

Check out this Ice Disk in the Presumpscot River in @downtownwestbrook @cityofwestbrook #icedisk #westbrookmaine

The photo and a new videos have since been shared by outlets across the world and gained the city some much-appreciated publicity.