Twice every year, in the US state of Hawaii, shadows completely disappear.
This natural phenomenon Hawaiians call Lahaina Noon and is as a direct consequence of the Sun’s position in relation to the Earth.
When the sun is in the position that the rays hit the surface at exactly 90 degrees, emitted light will be fall directly below an object. Since the angle between the location of the sun and any object is what casts a shadow, shadows are mostly eliminated when these angles are aligned. At that moment objects that stand straight up (flagpoles, telephone poles, etc.) cast no shadow giving the urban landscape an strange appearance.
What makes this phenomenon even more interesting is the fact that nature is played with our sense of sight.
The human brain throughout life develops the habit of using shadows as indicators and interpreters of various things. Some of them are size, movement, and time of day. The absence of shadow can affect the brain’s ability to handle visual stimuli. That’s why people can get the impression that objects look like they’re floating.
It should be noted that the described phenomenon is not reserved solely for Hawaii. It occurs in all areas that are 23.5 degrees south and north of the equator and it’ll only occur twice a year. In Hawaii, in late May and mid-July.
So, each day the subsolar point tracks westward across the earth moving north and south between the Tropic of Cancer and the Tropic of Capricorn and at this point shadows disappear completely resulting in a perplexing phenomenon.
A 1975 sculpture by Isamu Noguchi in Hawaii’s largest city take full advantage of this astronomical phenomenon. “Sky Gate” has a bendy, bumpy ring which drastically changes height as it goes around. For 363 days of the year it will make a curvy, twisted shadow, but when the sun is directly above it, the height-changing ring casts a perfect circle on the ground.