Unraveling Earth's Circumference: The Ingenious Method of Eratosthenes

In ancient times, when the concept of a spherical #Earth was still taking root, #Eratosthenes, a polymath from ancient Greece, made a groundbreaking discovery that revealed the Earth's circumference. Born in Cyrene (modern-day Libya) around 276 BCE, Eratosthenes' contribution to #geography and #mathematics remains unparalleled.

Eratosthenes' method for measuring the Earth's circumference was both simple and ingenious. He noticed that on a specific day each year, the summer solstice, the Sun would cast no shadow on the town of Syene (now Aswan, Egypt) due to its proximity to the Tropic of Cancer. However, in #Alexandria, a city to the north of Syene, a shadow was still cast by a vertical object such as a sundial or a vertical stick. Eratosthenes realized that this difference in shadow angles could be used to calculate the Earth's circumference.

Using basic #geometry, Eratosthenes measured the angle of the shadow cast in Alexandria and the distance between Syene and Alexandria. By applying principles of proportion, he estimated the Earth's circumference to be approximately 250,000 stadia, which is roughly equivalent to 40,000 kilometers – remarkably close to the modern-day value.

Eratosthenes' method was revolutionary not only for its accuracy but also for its reliance on empirical observation and mathematical reasoning. It demonstrated the power of scientific inquiry and laid the foundation for future advancements in geography and astronomy. His work helped to establish the spherical shape of the Earth and paved the way for further exploration and understanding of our planet's dimensions.

Today, Eratosthenes' legacy endures as a testament to the brilliance of ancient scholarship and the enduring quest for knowledge about our world. His method remains a shining example of how curiosity, ingenuity, and meticulous observation can unlock the mysteries of the universe.