Some of the world’s earliest astronomical observations were made by the ancient Chinese. Perhaps as early as 1500 B.C.E., Chinese astronomers created the first rough charts of space. In 613 B.C.E., they described the sighting of a comet. Within a few centuries after that, Chinese astronomers were keeping track of all the eclipses, sunspots, novae, meteors, and celestial and sky phenomena they observed.

Chinese astronomers made numerous contributions to the field of astronomy. They studied, for instance, the question of Earth’s motion and created one of the earliest known calendars. By the fourth century B.C.E., Chinese astronomers had produced a number of star charts, which depicted the sky as a hemisphere—a perfectly logical strategy, since we can only see half the sky at any one time. Three centuries after that, Chinese astronomers began to regard space as an entire sphere, showing they were aware of Earth’s spherical shape, as well as of Earth’s rotation around its polar axis. They created an early map of the celestial sphere on which they placed stars in relation to the Sun and to the North Star.

Chinese astronomers were the first to observe the Sun; they protected their eyes by looking through tinted crystal or jade. The Sung Dynasty, which began in 960 C.E., was a period of great astronomical study and discovery in China. Around this time, the first astronomical clock was built and mathematics was introduced into Chinese astronomy.