Friday, the day of summer solstice, saw a unique experiment of Qutb Minar turning into an astronomy lab. The World Heritage Site was used as scientific/astronomical equipment.
On June 21, the day of summer solstice, Ujjain — which has Jantar Mantar (set of astronomical equipment), situated on the Tropic of Cancer — does not register a shadow.
Science Popularisation Association of Communicators and Educators (SPACE) decided to use the 73-metre tall Qutb Minar to measure the shadow to know the angle of sunrays.
"At 12 noon, the shadow of the Qutb Minar from its base was just 0.9 metres," said SPACE's Chander Bhushan Devgun. Using the Pythagoras Theorem and Ujjain's distance as the crow flies, the angle was calculated at 5 degrees.
Erato Sthenes, a librarian at Alexandria (today's Greece), had carried out this experiment for the first time 2300 years ago. While SPACE has been carrying out these kinds of readings at Jantar Mantar, the 18th century set of astronomical instruments, this was the first time it was done at Qutb Minar.
"This was a good case of 'hands-on-science'... an experiment in science and geography using a heritage site," said a senior ASI official.
Approximately putting 1 degree for 100kms, earth's circumference can be calculated, Devgun said.
"Science cannot be taught just with high-tech instruments. And if one is observant about things around, one can learn science in day to day life too," he added.