Zero Shadow Day

333 reviews
Content rating
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About this app

Zero Shadow is a phenomenon when the sun is exactly overhead and the shadows of symmetrical and vertical objects vanishes. This happens for locations between the tropics and is caused by the northern and southern motion of the sun during the course of a year. This app helps you find the Zero Shadow Day for any location.

If you are between Tropic of Cancer and Tropic of Capricorn, then on a particular day (one during Uttarayan and other during Dakshinayan) the Sun will pass directly overhead at local noon. At local noon on this day, a vertical pole will cast no shadow. These are called Zero Shadow Days, or ZSD. This app is an aid to the campaign by the Public Outreach and Education Committee of the Astronomical Society of India for celebrating ZSD.

Inputs and Content by
Dr. Niruj Mohan Ramanujam, ASI POEC
Translations by:
Kannada - Dr B.S. Shylaja of Jawaharlal Nehru Planetarium Bengaluru and Mrs. Jyotsna
Telugu - Teja Teppala
Marathi - Dr. Aniket Sule, HBCSE, ASI POEC.
Hindi - Alok Mandavgane
Spanish - Alvaro Jose Cano Mejia from Colombia
Portuguese Brazilian - José Roberto Vasconcelos Costa
Updated on
Apr 23, 2024

Data safety

Safety starts with understanding how developers collect and share your data. Data privacy and security practices may vary based on your use, region, and age. The developer provided this information and may update it over time.
No data shared with third parties
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No data collected
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Ratings and reviews

325 reviews
Ramnath Vaidyanathan
April 24, 2024
filled with facts and multiple sims to keep the user engaged. thanks dev
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Mark D60
June 26, 2024
Very good app, it tells you when the sun will be directly overhead at your location in the tropics. Very good app, but highly specialized.
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Sarthak Choudhary
July 14, 2020
Gets the job done! Simple to use. Teaches important concepts in astronomy. It would be nice if the app author could provide resources as how to calculate the zero shadow day ourself for those who want to learn to do it.
16 people found this review helpful