Zero Shadow Day

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What is Zero Shadow day?

• Zero Shadow day is an unique event that takes place twice a year at locations between +23.5 and -23.5 degrees latitude. 
• On this day, the Sun will be directly overhead and hence any vertical object will not cast a shadow.
• According to the Astronomical Society of India (ASI), when the Sun is precisely at the zenith position, it will not throw a shadow on an object.
• The Sun is almost never exactly overhead at noon but usually transits a bit lower in altitude, a bit to the north or a bit to the south.
• The phenomenon occurs when the sun’s declination matches the location’s latitude. 
• Even though it just lasts for a second, the impact can be observed for around two minutes.

The Astronomical Society of India-

• It is an Indian society of professional astronomers and other professionals from related disciplines. 
• It was founded in 1972, with Vainu Bappu being the founder President of the Society, and as of 2010 has a membership of approximately 1000.
• Its registered office is at the Astronomy Department, Osmania University, Hyderabad, India. 
• Its primary objective is the promotion of Astronomy and related branches of science.
• It organises meetings, supports and tries to popularise Astronomy and related subjects and publishes the Bulletin of the Astronomical Society of India.

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