Lake Superior is never boring. Nor is there one moonrise quite like another. That’s why if the sky is clear and the moon is near full — and occasionally when it’s not — I make a point of watching it come up over the big lake. In a city thronged with trees it’s the only refuge for horizon-seekers.

Last night’s sky wasn’t promising. Scattered clouds scuttled about as a blanket of overcast climbed up from the western horizon. A strong wind hammered my back, but at the appointed moment, a tiny spot of bright light appeared in the distance and slowly grew into one of the weirdest moonrises I’ve ever witnessed.

Refraction flattened the rising moon into a cookie, but as it continued to rise, I watched in disbelief as the fluttering apparition morphed into a gumdrop and ultimately a water tower as if glued to the horizon and struggling to break free. When the final strands of light connecting the upper and lower images snapped, the moon hovered over what looks like its reflection in the water.

The familiar hot road mirage. The rear end of the car appears upside-down in the “pool” of water. (Brocken Inaglory)
The familiar hot road mirage. The rear end of the car appears upside-down in the “pool” of water. (Brocken Inaglory)

That was no reflection. It’s a mirage! Then entire sequence show the progress of an inferior mirage. If you drive a car you’ve seen the same mirage on a hot summer day when the road ahead looks like it’s covered in water. The “water” is actually an image of the sky overhead, and if you look closely the next time you’re on the road you’ll also see an inverted image of the car in the water.

In an inferior a big difference in the air temperature at ground or water level compared to the air above causes some of the light rays leaving a distant object to be bent down and then up to your eyes, creating the illusion of a second image below it. (Ludovica Lorenzelli / Density Design Research)
In an inferior a big difference in the air temperature at ground or water level compared to the air above causes some of the light rays leaving a distant object to be bent down and then up to your eyes, creating the illusion of a second image below it. (Ludovica Lorenzelli / Density Design Research)

What looks like water is really sky. When light from the sky passes from cooler air to the hot air immediately above the roadway, it’s bent upward and into your eyes, showing you what appear to be puddles. This mirage is common in deserts as well, leading thirsty hikers to think there’s water just beyond the hills.

When it comes to the sky the unexpected leads to a better understanding of one’s environment and opens our eyes to nature’s eternal creativity.

Read more from "Astro" Bob King at astrobob.areavoices.com.