The photo above appears to show a space-ship like object hovering above the sea. It’s actually a superior mirage of a lake freighter on Lake SuperiorPhotographer Randy Lane

These immense ships are sometimes over 1,000 ft (300 m) long. This one is likely 16 mi (26 km) distant, which is the approximate distance from shore to the shipping lanes. I took the picture from Two Harbors, Minnesota on October 21, 2010 with the camera facing east. The air temperature at the time (7:20 a.m.) was about 35 degrees F (2 C), and the water temperature was perhaps 20 degrees F (11 C) warmer. A layer of cooler air was trapped between the lake water and warmer air just above creating a temperature inversion.

With a superior mirage, an object looks higher than its true position. Rays of light are bent or refracted downward by the inversion –light refracts toward the more dense medium. Note that the horizon looks to be rather rough. This looming (of waves) is a signature of mirages.