A giant spinning wheel of ice on the surface of the Presumpscot River has enthralled crowds in Westbrook, Maine since Monday, January 14, 2019. Many locals have likened it to crop circles –strange patterns that appear mysteriously overnight in farmers' fields, which have long been theorized to be markers of extraterrestrial communication – and speculated that the icy ring is a landing site for an alien ship. Unfortunately for UFO enthusiasts, experts say that the rare winter phenomenon is a natural occurrence.
Most scientists agree that the disks form when slush, or ice, freezes on the surface of a moving body of water, usually at a bend in the river or stream. However, there is some debate about what causes them to spin. A 1997 study published in the Royal Meteorological Society theorized that the force of the water current pushing the ice results in a whirlpool or eddy beneath it and causes it to spin. As the piece of ice rotates, its edges hit surrounding rocks and get smoothed and transformed into a near perfect circle.
However a 2016 study, published in the scientific journal,Physical Review E, asserts that while river currents may help initially form the disk, it is the changing temperature that helps maintain its rotation. According to the researchers, when ice melts on top of a slightly warmer river, a vortex, caused by the heavier cold water encountering the less dense warm water, is created. They believe it is this whirling underground water column that causes the ice to rotate, and note that the warmer the water on the bottom, the faster the disk spins.
But University of Southern Maine physicist Paul Nakroshis is doubtful this theory holds for Westbrook’s spinning ice plate. In a conversation with Maine Public Radio, he noted that the river is not warm enough for melting ice to be the cause. “Most likely the cause of the rotation is just the river water going by the disk,” he said, adding, “Once it starts rotating in that direction, it’s probably going to continue.”
Regardless of how it formed or what causes it to rotate, Westbrook residents are enjoying their swirling plate, which measures an impressive 300 feet in diameter and is much larger than most reported ice disks, which span a mere 20 or 30 feet across. Though some meteorologists had feared the severe winter storm, which swept through the area this past weekend, would freeze it in place, the apprehension proved unfounded. On Sunday, January 20, 2019, Westbrook officials reported that the magnificent disk appeared to have become even larger and was spinning as furiously as before. The extension of the incredible winter phenomenon will not only allow the locals to enjoy it for a few more days but also enable scientists to study the disk in further detail and perhaps solve the mystery of its rotation once and for all!
Resources: nationalgeographic.com, pbs.org, the city of Westbrook facebook, Gizmodo, com, pressherald.com