HYDERABAD: With the weather and the Sun playing Hide and Seek with us; if all goes well and we can see our Sun, then we will be able to enjoy the second Zero Shadow Day phenomenon at the BM Birla Planetarium, Hyderabad on 3rd August 2023 at 12.23 pm.
This is an interesting phenomenon to observe that occurs twice a year when the sun is directly overhead and thus no shadow of any vertical object can be seen. The phenomenon occurs because of the tilt of the Earth's axis and its rotation around the sun. This tilt causes the angle of the sun's rays to change throughout the year, which in turn shows various lengths and directions of shadows.
The axis about which the earth rotates is tilted at an angle of 23.45 degrees to the plane of the earth's orbital plane and the sun's equator. The Earth's axis results in a daily variation of the angle between the earth-sun line and the Earth's equatorial plane called the solar declination.
The Zero Shadow Day (ZSD) phenomenon occurs when the Sun's declination becomes equal to the latitude of the location. On a zero shadow day, when the sun crosses the local meridian, the sun's rays will fall exactly vertically relative to an object on the ground and one cannot observe any shadow of that object.
Zero shadow day happens for locations between the Tropic of Cancer and the Tropic of Capricorn.
The latitude of Hyderabad is 17.3850° N. ZSD will be seen in Hyderabad on 03rd August 2023 at 12:23 IST. The shadow of any vertical object would appear to disappear at this instant.
Actually, the shadow does not disappear but it is located right under the object, and in our case, it is under our feet.
Subject to the weather condition and appearance of the Sun the ZSD event will be demonstrated at BM Birla Planetarium on 3 August 2023 from 12 noon onwards till the no shadow period.
If you are trying experiments related to ZSD at your home you can share the images of your efforts to birlasc@gmail.com.
Do you know that by comparing the shadow length at a distant city situated in the same longitude at the same time as ZSD in our city the circumference of the earth can be calculated?
This day the following places will also witness ZSD at the same time:
Places Latitude and Longitude
Chiplun, Maharashtra 17.5319° N, 73.5151° E
Mandrup, Maharashtra 17.4948° N, 75.8214° E
Akkalkot, Maharashtra 17.5242° N, 76.2054° E
Hyderabad, Telangana 17.3850° N, 78.4867° E
Kothagudem, Telangana 17.5560° N, 80.6170° E
