Astronomy buffs observed Zero Shadow Day on Monday, within the confines of their homes, during the COVID-19 lockdown.
The Pondicherry Science Forum had disseminated information among schoolchildren on observing the phenomenon while staying home. The details were also made available on a mobile app.
According to the forum, Zero Shadow Day is distinctly different for various places on earth.
On a day when the latitude of a place equals the declination of the sun, the sun’s rays are perpendicular on the latitude. Exactly at noon, the sun is right overhead, and the shadow of a vertical object falls right below.
For Puducherry, the latitude is about 11.9 degree.
On April 20, the sun’s declination (the angle of the sun’s rays falling on the equator) was 11.9 degree, and since the region is inclined at the same angle with respect to the equator, the sun’s rays fell perpendicular at noon, in Puducherry, around 12.16 p.m. (since the region is about 4 degrees to the west of the IST referral point), the forum said.
