Astronomy is the oldest natural science and has calendrical, religious, cosmological, mythological and astrological origins. Long before famous monuments like Stonehenge in England and the pyramids of Egypt were constructed, ancient people around the world built elaborate observation platforms and monumental structures aligned to the positions of the sun, moon and stars on the horizons on significant dates in their calendars, often marking days, weeks and months, which were important to both hunter-gatherer and agricultural societies.
Dated to 1600 BC, The Nebra sky disk is a 30-centimeter (12 inch) diameter bronze disk weighing around 2.2 kilograms (4.9 pounds). The disc features a blue-green patina and is inlaid with gold astronomical symbols including the sun, full moon, a lunar crescent moon and a cluster of stars interpreted as the Pleiades constellation. (CC BY-SA 3.0)
The earliest star gazers were able to differentiate between stars and planets stars, as while stars remained apparently fixed over the passage of centuries, planets moved around the sky during comparatively short periods of time. Ancient people associated natural phenomena such as seasons, rain, heat, drought and tidal change with gods and spirits, as manifestations of Divine Will, and ancient astronomical structures fulfilled astronomical and religious functions.
Before Julius Caesar reformed the calendar in 46 BC, introducing the so called ‘Julian calendar’ which is based on a 365 and a quarter day year, ancient astronomers traditionally linked the month to the phases of the moon and all over the world sky watchers created calendars of twelve almost-equal months, varying between 30 to 31 days. To gain a fuller understanding of which specific celestial occurrences were important to the first astronomers, and to better understand their motives, one must look beyond the modern calendar and venture to a time where the pyramids and vast stone circles were but a celestial dream.
