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Zero Shadow Day

 

Source: IE

Context: Recently, Bengaluru experienced a ‘Zero Shadow Day’, when vertical objects appear to cast no shadow.

 

About Zero Shadow Day:

Description
DefinitionZero Shadow Day is a phenomenon where the sun is exactly overhead and vertical objects appear to cast no shadow. It happens twice a year for every point on Earth between the Tropic of Cancer and the Tropic of Capricorn.
CausesEarth’s rotation axis is tilted at an angle of roughly 23.5° to the axis of revolution around the Sun
OccurrenceOne day during Uttarayan (Sun moves northwards from winter solstice to summer solstice) and one day during Dakshinayan (Sun moves southwards from summer solstice to winter solstice)
LatitudeOccurs at latitudes equal to the angle between the Sun’s location and the equator on that day
Bengaluru ExampleExperienced Zero Shadow Day on April 25, 2023, at 12:17 pm local time along 13-degree Latitude, with the next one expected on August 18, 2023
 

As the Earth revolves around the Sun, it also rotates on its axis. During the year, the Sun’s location moves from 23.5 degrees south of the celestial equator to 23.5 degrees north of the equator (Uttarayan), and then back again (Dakshinayan). All places whose latitude equals the angle between the Sun’s location and the equator on that day experience Zero Shadow Day