An astrarium, also called a planetarium, is the mechanical representation of the cyclic nature of astronomical objects in one timepiece. It is an astronomical clock.

The first astraria were mechanical devices. Archimedes is said to have used a primitive version that could predict the positions of the sun, the moon, and the planets. On May 17, 1902, an archeologist named Valerios Stais discovered a lump of oxidated material with in it a mechanism with cogwheels that had been recovered from a shipwreck near Antikythera. This mechanism, known as the Antikythera mechanism, was recently redated between [150 to 100 BC][1]. Extensive study of the fragments, using X-rays, have revealed enough details (gears, pinions, crank) to enable researchers to build partial replicas [2], [3][4]. Engraved on the major gears are the names of the planets (such as Venus), which leaves little doubt as to the intended use of the mechanism.

However, before the end of the Roman Empire, the know-how and science behind this piece of clockwork would be lost.

Leon Bolier (Dutch pronunciation: [ˈle.joʊ̯n boʊ̯.ˈliːr]; born 1980) is a Dutch classically trained trance composer, DJ, and record producer. His career began to flourish in 2008 with a number of successful song releases including the hit song "Ocean Drive Boulevard". He placed #95 on DJMag's 2008 list of the top 100 DJ's in the world, and moved up 32 places in 2009, and rests at #68 in 2010. He has had his songs played by top DJs like Tiësto and Armin van Buuren as well as his tracks appearing on famous trance compilations such as In Search of Sunrise 4: Latin America and A State of Trance 2006. His latest album, Phantasma, was released on August 30, 2010.