A nightly light show in the forest
In a remote valley in Michigan's Upper Peninsula, a bright light appears almost every clear night. First officially reported in 1966 by a group of teenagers, the Paulding Light has become a consistent local phenomenon. The light materializes in the distance down a tree-lined valley, viewable from a dead-end gravel road called Robbins Pond Road (also known as Old US-45). Observers describe a single, bright orb that can be white, red, or even green. It hovers above the treeline, sometimes flickering, changing in size and brightness, and then vanishing.
The most common explanation involves the supernatural. Local folklore often says the light is the ghost of a railroad brakeman killed on duty. The story suggests the valley once held train tracks, and the light is the brakeman's lantern as he eternally walks the line. Other tales mention a murdered mail courier or the spirit of a Native American dancing on the power lines that run through the area.
The site is marked with a sign and is a tourist attraction that draws crowds who gather at the guardrail overlooking the valley where the old highway disappears into the woods.
A scientific investigation
In 2010, a group of students from the Michigan Technological University chapter of the Society of Photo-Optical Instrumentation Engineers (SPIE) decided to investigate the phenomenon. Led by PhD candidate Jeremy Bos, the team brought a telescope to the viewing site on Robbins Pond Road. When the light appeared, they looked through the telescope and saw the headlights of a car.
To confirm their observation, the students identified the specific stretch of highway, a section of US-45 approximately 4.5 to 5 miles north of the viewing spot. They were able to pinpoint the location by identifying a specific "Adopt a Highway" sign through their telescope and finding it on a map. The team then conducted a coordinated experiment. One student drove a car along that part of US-45 while others at the viewing site logged the appearances of the Paulding Light. The timing correlated exactly.
The investigation concluded that the light is an optical illusion. The specific geography of the valley, combined with a stable atmospheric temperature inversion, allows headlights from the distant highway to become visible. The inversion layer, where a layer of cold air is trapped beneath warmer air, can bend light rays, making the headlights appear to hover and move erratically as cars travel up and down a hill on US-45. Variations in intensity are simply drivers using high and low beams.