Thousands of years ago, with no artificial light scattering in the atmosphere, people from various ancient civilizations gazed into the night sky with profound awe and wove the celestial patterns into their mythology while also basing their calendars on them. The stars guided navigation and agricultural timing, and many people sought meaning and patterns in the ever-moving canvas of the sky. However, while the Sumerians, Egyptians, and other cultures had practical incentives to develop early astronomy, the ancient Greek philosophers did not separate scientific and philosophical disciplines. Philosophy was considered an attempt to understand the entire cosmos and not just a part of it, so every aspect of life and every observable thing might be considered under the umbrella of philosophy, including technology and art. Indeed, it was the ancient Greek philosophers who devised the very concept of technology.
For the ancient Babylonians and Egyptians, sky watching served religious or practical purposes, but for the Greeks, it was also theoretical. They wanted to know why heavenly bodies moved as they did, and for that reason, the Greeks added mathematics, geometry, and philosophical reasoning to the crucial foundational data of the Sumerians, Babylonians, and Egyptians. By the 5th century BCE, Pythagoras proposed that the world was not flat, but a sphere, Anaxagoras explained why eclipses happened and described meteorites, and Leucippus and Democritus wrote that tiny, invisible atoms were the building blocks of the entire universe. By the 3rd century BCE, Aristarchus of Samos taught that Earth rotated on its axis each day and revolved around the Sun each year. Eratosthenes used geometry to calculate the distance around Earth from pole to pole, and he came unbelievably close to precisely accurate measurements. Thanks to these scientific pioneers and their works, the Greeks laid the cornerstone of modern astronomy.
