Mysore/Mysuru: The Cosmology Education and Research Training Centre (COSMOS), Mysuru and the Indian Institute of Astrophysics (IIA), celebrated “Zero Shadow Day” on Apr. 22 at Shishu Loka, Kuvempunagar in association with Putani Parapancha Summer Camp.

N. Amoghavarsha, Project Associate of COSMOS, delivered a lecture on the science behind Zero Shadow Day. Later, hands-on experiments and demonstrations were shown to participants by Vikranth Pulamathi, Project Associate of SCOPE, IIA.

Students were asked to take readings of the length of shadow made by Gnomon (“Shan khu Yantra”) for every five minutes to note down changes in shadow. Zero Shadow Phenomenon was observed at 12.22 pm which was demonstrated by a hollow cylinder kept on a glass plate.

R. Punith, K.B. Vishaak of IIA were also present during the programme which concluded with a question and answer session.

Zero Shadow Day (ZSD) occurs when the Sun is directly overhead (that is, at the zenith). At this moment, any object held vertically will not cast any shadow on the ground, since the Sun’s rays fall straight down on it, rather than at an angle. On other days, the Sun is not exactly overhead at noon.

Only locations lying between the Tropic of Cancer and the Tropic of Capricorn will experience ZSD, which will occur twice a year; corresponding to the northern and southern movement. Since the Earth is tilted on its axis by about 23.5 degrees, as the Earth revolves around the Sun, the Sun can pass overhead only for locations whose latitude lies between 23.5° N and 23.5° S. Hence, different locations experience ZSD on different days. For details contact Mob: 63621- 59474.