Star trails: From pocket planetarium to giant dome

HEAVENS ON EARTH } BUILT TO SCALE

- Anesha George

Ancient Babylonians built watchtowers to study the sky, and used clay tablets to record the positions of ritually significant stars.

That was c. 2000 BCE.

By the 1st century BCE, the Ancient Egyptians were portraying the night sky in intricate detail. One such astral disc was fixed to the ceiling of the Hathor temple. The wheel-like structure features constellations associated, in startlingly familiar ways, with animals such as the ram, lion and bull.

The wheel was detached, when Egypt was colonised by France, and is now at the Louvre in Paris.

By the 3rd century BCE, the Greek polymath Archimedes is said to have crafted a metal model depicting planetary movements, in an early example of a mechanical planetarium.

The device was taken from him, during a Roman invasion, but records of it survive in the writings of Roman statesmen such as Cicero.

By the 17th century, the closest predecessor to the modern planetarium had been created.

The Gottorf Globe, built by 1664, was a massive walk-in sphere commissioned by Duke Frederick III of Holstein-Gottorp (in present-day Germany), a patron of the sciences and arts. Its exterior was painted to resemble a map of Earth, with continents and oceans. The dark interiors replicated a starry night, through the use of pinholes punched into the orb. Visitors sat on a circular bench, while the globe was rotated with levers and gears.

Ceiling plan

The world's oldest still-operational "planetarium" dates to 1781, and it is a marvellous contraption built by an amateur astronomer, to counter a terrifying rumour: that a catastrophic planetary alignment between the Sun, Moon and five other known planets (Mercury, Venus, Mars, Jupiter and Saturn) was about to destroy Earth.