VESTABURG, Mich. (WOOD) — Viewers may be skeptical of the video clip below showing a perfectly circular ice disc spinning in the Pine River, but the phenomenon is completely natural.
The ice disc is also known as an “ice pan” or “ice circle,” and exactly it how it forms has been mystifying scientists for decades.
The discs, which can range in size from 3 feet to almost 700 feet, have been spotted across countless cold climates. Several states in the U.S. have reported natural ice discs, as have Scandinavian countries.
For years, the water current was believed to have caused the discs to spin — they were thought to have been caught in a swirl of water called an eddy. Recently, that idea was found to be incorrect. If the water was spinning the solid rings of ice, then smaller discs would spin faster than larger discs, but research proved that all the discs spin at the same rate.
The spinning has to do with the density of water when in ice form and liquid form, and how it melts. One lead scientist has proven that the discs are spinning because they’re melting and the melting, sinking water turns the ice at a pretty constant speed. For a detailed explanation, check out this article featuring the scientist who discovered the source of the spinning, Stéphane Dorbolo.