Stars on oldest heliocentric model were on backwards
One of the world's oldest mechanical models of the universe has been on display with its constellations in the wrong order for more than 60 years. But - until I found myself scratching my head at its unveiling to the public following a year-long restoration - it seems that no one had noticed. The Leiden Sphaera, a top attraction in Museum Boerhaave (the Dutch National Museum for the History of Science and Medicine in Leiden), was built around 1670 by the clock maker Steven Tracy for Adriaen Vroesen, a mayor of Rotterdam with a keen interest in science. It is a very early example of an orrery: a dynamic scale model of the solar system. According to Hans Hooijmaijers, head of collections at Museum Boerhaave, the Sphaera, which measures 1.5 metres across, may well be the first orrery ever to display the Sun-centred universe. Read more
The Leiden Sphere, a mechanical armillary sphere or orrery, was built around 1670 by the clockmaker Steven Tracy, for the mayor of Rotterdam. It is among the earliest and most elaborate mechanical planetaria to be operated by a clockwork mechanism. The device depicts the Copernican solar system, in which the Earth and the other planets revolve around a stationary sun. In order of distance from the sun, the Sphere includes Mercury, Venus, the Earth (with its moon), Mars, Jupiter with the four Galilean satellites, and Saturn. The mechanism in the base of the Sphere regulates an accurate representation of the orbital periods of each of the planets and their inclined orbits around the sun. Read more