New Delhi : SPACE the pioneer organization working towards the development of science and astronomy in India, today celebrated the day of 
Winter Solstice by conducting activities for students and a heritage walk with 50 people at Jantar Mantar. SPACE replicated an activity to calculate the circumference of the earth using shadows cast by the sun, previously done by Eratosthanes 2300 years ago, under its flagship project “Project PARIDHI”. Despite the fog, more than 100 school students from class VI to IX participated. 20 Schools from Delhi & NCR participated, including Bal Bharti Public School- Pitampura, Indraprastha International School – Dwarka-Sec-10, GD Goenka Public School-Sec-48-Gurgaon, DPS International School-Saket, Sachdeva Public school-Rohini, Suncity School-Gurgaon, Ryan International School-Rohini, ASN School-Mayur Vihar-New Delhi, Mayoor School-Noida Sec-126, Modern School, Barakhamba – New Delhi etc. The plan was to use the gnomon at Ram Yantra as well as Jai Prakash Yantra to measure the circumference. However, because of the haze this part of the activity could not be carried out. Instead, all participants were taken on a guided walk around Jantar Mantar and learnt about the usage of the ancient instruments. They also learnt how to calculate the circumference once sun angle is known.
SPACE Foundation President Mr. CB Devgun said that, “We are conducting this flagship project since 2010 with more than 20,000 school students. This time we had a guided walk for the public to describe the ancient archaeological instruments and how the ancient instruments were used for astronomy”. About 50 people participated in a guided walk around Jantar Mantar and learnt about the usage of the ancient instruments. We chose Jantar Mantar as location in order to make students understand the importance of preserving our heritage for future generation.”
Risa Goswami, a student co-ordinator from the Sakula Academy said, “I am very happy to be a part of the program and appreciate the experiment. Want to explore more and be a part of the event again.”
Tushar, a student from the Modern school, Barakhamba said, “It was a great experience, though we live in Delhi but we never get such an opportunity to visit and learn about such historical monuments. Thank you SPACE for giving us such an opportunity.”
21st December, 2013 is the day of Winter Solstice celebrated over the world in different ways. On this day the Sun is at its southernmost point in the sky, and is directly over the Tropic of Capricorn at 23.44 degrees south latitude at noon. This day is marked as the first day of winter in the northern hemisphere and the first day of summer in the southern hemisphere. As the position of the sun is well known on this day, it makes it optimal to do this activity on this day. The shortest day of the year, is on this day and this time on Dec 21st it was around 10 hours and 19 min long.
This experiment was first done by a very famous Greek Astronomer and Mathematicians Eratosthenes around 240 BC, where he calculated the circumference of earth using knowledge of the angle of elevation of the sun at noon. SPACE started this experiment in the year 2010 under its flagship project “Project PARIDHI” with an intention to increase awareness amongst Indians that science can be done without any complicated equipment. SPACE has previously conducted this project at various national heritages like Jantar Mantar, Qutub Minar and also by using the giant sundial constructed at Barapullah during the commonwealth games. This project encourages hands on science by enabling students to measure the shadows cast by the sun and using simple geometry and trigonometry to calculate the earth’s circumference from that.
With the help of this project conducted at our heritage site Jantar Mantar, SPACE has highlighted that such Indian monuments can be used as tools to demonstrate and get the common man interested in science. During last autumn equinox, 10% of the students measured the circumference with above 97% accuracy, and 90% of the students achieved 90 to 95% accuracy.
Source : Lokesh Shastri