ancient-science

Around 240 BCE, Eratosthenes measured Earth's circumference using two sticks and shadows. Here is exactly how he did it — and why the result was nearly perfect.

Archimedes discovered that objects submerged in fluid displace fluid equal to their volume, experiencing upward force equal to displaced fluid's weight.

Around 240 BCE, Greek mathematician Eratosthenes used only sunlight, shadows, and geometry to calculate Earth's circumference with remarkable accuracy. A timeless example of clever scientific thinking.