ছায়ায় মাপা পৃথিবী

Approximately 2200 years ago, without modern technology, the chief librarian of Alexandria, Eratosthenes, embarked on a mission to determine the Earth's circumference. He learned that in Syene (modern Aswan), on June 21st at noon, the sun cast no shadow, indicating it was directly overhead. Intrigued, Eratosthenes observed that in Alexandria on the same day and time, a vertical stick did cast a shadow.

This ancient calculation demonstrates the power of observation and geometry to understand our world, laying a foundation for scientific inquiry.