Zero Shadow Day: this is the curious phenomenon that makes shadows disappear twice a year in some places in the world

It is no secret that our shadow accompanies us everywhere we go, as long as there is light. But what if we told you that there are times when disappears almost completely? Twice a year, in some places around the world, a phenomenon known as “Zero Shadow Day” or “Day of Shadow Zero”.

And how is this possible? There is a very simple explanation behind this. These days, the Sun is right above our heads, in what is known as zenith. The sun’s rays fall in a way in which vertical objects such as flagpoles, bicycles, antennas, monoliths, etc., stop casting shadows.

Days of zero shadow, a surprising phenomenon

It is as if the shadow is fading over the earth’s surface. A very interesting spectacle to see in person and also photograph, of course. The only drawback is that shadowless days happen everywhere in the world, but in specific regions. Specifically, among the Tropics of Cancer and Capricorn.

The key to all this is the tilt of the Earth. Our planet rotates around the Sun with an inclination of about 23.5 degrees. This, which is what we owe the seasons to, also means that the point where the Sun hits fully moves throughout the year. We call that point the “subsolar point.”

As the Bishop Museum of Science and Nature explainsthe subsolar point is moving from the Tropic of Cancer, back on June 21, to the Tropic of Capricorn, about December 21and then makes his way back. For this reason, the phenomenon where shadows disappear is so limited.

For example, in India, Cities like Chennai and Bangalore have their own “Zero Shadow Day”. It also happens in Mexico City or San Juan de Puerto Rico. Even in Hawaii, they call this phenomenon “Lāhaina noon” and they experience it a couple of times a year, with dates that vary depending on the island.

Now, those of us who live further north of the Tropic of Cancer or further south of the Tropic of Capricorn will not have the possibility of experiencing this phenomenon. Although there will always be the possibility of traveling to a intertropical zone to give our shadow a rest, albeit too brief.

Images | Tmamatha | TNSC SHANMU VPM | Daniel Ramirez

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