Keeping an eye on the heavens helps to keep track of time and events on the Earth. All the calendars and astronomical instruments rely on the sun and the moon, the two most important astronomical bodies for us on planet earth..

Astronomy also plays an essential role in the organization of societies in general. Understanding the cycles of the sun and the moon was an essential condition for the development of our agricultural societies. Stonehenge is an example of the knowledge of the sky in prehistoric times. It was built on the basis of high-end mathematics and geometry and is aligned with the rising and setting of the sun and served as astronomic observatory.

Also religious dates are usually related to astronomical events. In Islam, they still use the moon calendar. As a result, the Islamic religious festivals happen on different dates every year. Ancient Egyptians and Mayans built observatories. The Egyptian obelisks for instance were used as shadow clocks. The citizens could divide the day into two parts and also into hours by following the obelisk’s shadow.

The Mayan had astronomical codices which allowed them to calculate moon phases and eclipses. They had a vast knowledge of the ecliptic, the zodiac as well as the Milky Way. Mayan priests recorded astronomical observations for centuries, noting the positions of stars and planets with incredible precision.

Most ancient cultures observed and worshipped the sky and tried to understand it.

In the year 276 B.C, Eratosthenes invented the armillary sphere. It was used to demonstrate the motion of the stars around the earth. It has been updated, reinvented and widly used until the present day to determine celestial positions.

The Antikythera Mechanism was probaly invented by Archimedes in the 100 B.C . It’s an analogic computer with a geocentric model. The Sun turns around the Earth like a 24 hours analog dial. It is able to predict moonphases and eclipses. This instrument remained in the bottom of the sea more than thousend years . After this mechanism no new instruments aproaching this complexity were invented in Europe until the renaissence.

It is interesting to note that the Middle East was a couple of centuries ahead of Medieval Europe on this subject area. The Astrolabe was widely used in the medieval Islamic world . This was an analog calculator that allowed users to determine the time accurately by looking at the stars. This instrument helped to schedule morning prayers, and to determine local time with local latitude by triangulation and the development of accurate calendars.

This knowledge was used by governments to make sure that tax collectors did not try to collect taxes before the harvest was in. True astrolabes were made before 400 A.D. and were highly developed in the Islamic world by 800 A.D. and were introduced to Europe from Islamic Spain (al-Andalus) in the early 12th century.

Umayyad Anonymous 1031. Kraków. Muzeum Uniwersytetu Jagiellonskiego.

The first astronomical clocks were built in the 13th century. Special mechanisms and dials were used to display astronomical information such as the relative positions of the sun, moon, zodiacal constellations, and sometimes major planets. European astronomical clocks are derived from the technology of the Antikythera mechanism. During the Islamic golden age and in Asia complex mechanisms such as water clocks were made.

“Most of the first clocks were not so much chronometers as exhibitions of the pattern of the cosmos … Clearly the origins of the mechanical clock lie in a complex realm of monumental planetaria, equatoria, and geared astrolabes” Lynn White Jr., medieval researcher

Some of these master timepieces are still working today.