Over 2,000 years ago, a Greek scholar named Eratosthenes became the first person in history to calculate the circumference of the Earth. He lived in Alexandria, Egypt, and knew that in the city of Syene (now Aswan), the Sun shone directly into deep wells at noon during the summer solstice. By comparing the angle of the Sun’s rays in Alexandria with those in Syene, and knowing the distance between the two cities, he was able to estimate the size of the Earth with remarkable accuracy.

In this activity, you will follow a similar approach using maps and coordinates of Indian cities. You’ll measure distances, calculate angles, and estimate the Earth’s circumference, just like Eratosthenes did centuries ago.