When Shadows Disappear

April 11, 2017

Notice anything odd about this picture? The sun is out as you can tell by the shadows under the cars and on the walls. But why aren’t the yellow poles casting any shadows?

lahaina-noon-1

It appears as if someone cut out the poles from another picture and pasted it here. That, or it’s a screenshot from a badly rendered videogame where the developer forgot to turn on the shadows. But I can assure you it’s a real picture, and it was taken in Hawaii.

The reason why there are no shadows is because the sun is directly overhead. The Hawaiians call this phenomenon the Lahaina Noon.

Hawaii is the only state in the United States where this phenomenon occur, twice every year, but it isn’t the only place on earth where this happens. In fact, there is a point on earth now, as you are reading this, where the sun is casting no shadow at all. That point is constantly moving across the surface of the earth, as the planet rotates. Probably, it’s now in the middle of an ocean, or in the desert, or at some obscure place where the phenomenon is difficult to observe or no one to notice them.

This point is called the subsolar point. At the subsolar point the sun's rays hit the planet exactly perpendicular to its surface, so any perpendicular object will cast no shadow. This shadow-less phenomenon was coined “Lahaina Noon" by the Bishop Museum in Hawaii, referring to the old Hawaiian capital Lahaina, on the Island of Maui. “La haina” means "cruel sun" in the Hawaiian language.

As the earth rotates, the subsolar point moves westward, circling the globe once a day. It also moves north and south between the Tropic of Cancer and Tropic of Capricorn. When the subsolar point is on the Tropic of Capricorn, it’s the day of the December solstice and the June solstice is at the instant when the subsolar point is on the Tropic of Cancer. Similarly, March and September equinoxes occur when the subsolar point crosses the equator.

The dates when Lahaina Noon occur changes from year to year. The first one occurs in May, and the second one in July. The time is usually between 12:16 to 12:43 p.m. Hawaii-Aleutian Standard Time. You can checkout your local calendar or search on Google for the exact dates and coordinates.

Subsolar_point