---
title: "History of astronomy"
chunk: 2/11
source: "https://en.wikipedia.org/wiki/History_of_astronomy"
category: "reference"
tags: "science, encyclopedia"
date_saved: "2026-05-05T03:59:16.412764+00:00"
instance: "kb-cron"
---

The Nebra sky disc is a Bronze Age bronze disc that was buried on Mittenberg hill in Germany around 1600 BC. It measures about 30 cm (12 in) diameter with a mass of 2.2 kg (4.9 lb) and displays a blue-green patina (from oxidization) inlaid with gold symbols. Found by archeological thieves in 1999 and recovered in Switzerland in 2002, it was soon recognized as a spectacular discovery, among the most important of the 20th century. Investigations revealed that the object had been in use around 400 years before burial (2000 BC), but that its use had been forgotten by the time of burial. The inlaid gold depicted the full moon, a crescent moon about 4 or 5 days old, and the Pleiades star cluster in a specific arrangement, forming the earliest known depiction of celestial phenomena. Twelve lunar months pass in 354 days, requiring a calendar to insert a leap month every two or three years in order to keep synchronized with the solar year's seasons (making it lunisolar). The earliest known descriptions of this coordination were recorded by the Babylonians in the sixth or seventh centuries BC, over one thousand years later. Those descriptions verified ancient knowledge of the Nebra sky disc's celestial depiction as the precise arrangement needed to judge when to insert the intercalary month into a lunisolar calendar, making it an astronomical clock for regulating such a calendar a thousand or more years before any other known method.
The Kokino site, discovered in 2001, sits atop an extinct volcanic cone at an elevation of 1,013 metres (3,323 ft), occupying about 0.5 hectares overlooking the surrounding countryside in North Macedonia. A Bronze Age astronomical observatory was constructed there around 1900 BC and continuously served the nearby community that lived there until about 700 BC. The central space was used to observe the rising of the Sun and full moon. Three markings locate sunrise at the summer and winter solstices and at the two equinoxes. Four more give the minimum and maximum declinations of the full moon: in summer, and in winter. Two measure the lengths of lunar months. Together, they reconcile solar and lunar cycles in marking the 235 lunations that occur during 19 solar years, regulating a lunar calendar. On a platform separate from the central space, at lower elevation, four stone seats (thrones) were made in north–south alignment, together with a trench marker cut in the eastern wall. This marker allows the rising Sun's light to fall on only the second throne, at midsummer (about July 31). It was used for ritual ceremony linking the ruler to the local sun god, and also marked the end of the growing season and time for harvest.

Golden hats of Germany, France and Switzerland dating from 1400 to 800 BC are associated with the Bronze Age Urnfield culture. The Golden hats are decorated with a spiral motif of the Sun and the Moon. They were probably a kind of calendar used to calibrate between the lunar and solar calendars. Modern scholarship has demonstrated that the ornamentation of the gold leaf cones of the Schifferstadt type, to which the Berlin Gold Hat example belongs, represent systematic sequences in terms of number and types of ornaments per band.  A detailed study of the Berlin example, which is the only fully preserved one, showed that the symbols probably represent a lunisolar calendar. The object would have permitted the determination of dates or periods in both lunar and solar calendars.

== Ancient times ==

Early cultures identified celestial objects with gods and spirits. They related these objects (and their movements) to phenomena such as rain, drought, seasons, and tides. It is generally believed that the first astronomers were priests who believed celestial objects and events to be manifestations of the divine, hence the connection to what is now called astrology. 
Calendars of the world have often been set by observations of the Sun and Moon (marking the day, month, and year) and were important to agricultural societies, in which the harvest depended on planting at the correct time of year. The nearly full moon was also the only lighting for night-time travel into city markets.
The common modern calendar is based on the Roman calendar. Although originally a lunar calendar, it broke the traditional link of the month to the phases of the Moon and divided the year into twelve almost-equal months, that mostly alternated between thirty and thirty-one days. Julius Caesar instigated calendar reform in 46 BC and introduced what is now called the Julian calendar, based upon the 365+1⁄4 day year length originally proposed by the 4th century BC Greek astronomer Callippus.

=== Mesopotamia ===