Zero Shadow Day: All About Rare Astronomical Event In Bengaluru Today

India's Silicon Valley, Bengaluru is set to witness a unique astronomical phenomenon called Zero Shadow Day today. At 12:24 pm, residents will have the opportunity to witness how shadows disappear during this astronomical phenomenon. Zero Shadow Day takes place when the sun is positioned directly overhead, casting no shadow on Earth's surface. During this specific time, all vertical objects become shadowless.  Bengaluru previously observed Zero Shadow Day on April 25.

What Is Zero Shadow Day?

Zero Shadow Day occurs twice every year in locations between the Tropics of Cancer and Capricorn, where the Sun is positioned directly overhead at noon. The shadow typically appears elongated on the ground while being observed under normal circumstances. However, when the shadow perfectly aligns under the object, during a short period of time, it remains absent on the ground. This happens when the sun reaches the zenith, its highest point of revolution.

Why does Zero Shadow Day occur?                             

Zero Shadow Day is caused due to Earth's axial tilt of approximately 23.5 degrees and its orbit around the Sun.  The Sun is never overhead causing it to maintain a slightly lower altitude either north or south. The tilting position is also responsible for different seasons on Earth. As the Earth orbits the sun, the angle at which the sun's rays hit the Earth's surface changes, causing shadows to be cast in different directions. In regions falling between the Tropic of Cancer (about 23.5 degrees north of the equator) and the Tropic of Capricorn (about 23.5 degrees south of the equator), there are instances when the Sun is exactly overhead. Since the sun's rays come down almost vertically, there is no or little shadow on vertical objects.

When Does Zero Shadow Day Occur?

The Zero Shadow typically happens twice every year in tropical regions at the time when the Sun crosses the zenith point. The dates of the occurrence may vary depending on the specific location and its latitude.