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. A mechanism is some technical aspect of a larger process or mechanical device, a part or combination of parts designed to perform a particular function. ... See also Lists of astronomical objects Category: ... Prague astronomical clock Astronomical clock in Lund Cathedral An astronomical clock is a clock with special mechanisms and dials to display the relative positions of the sun, moon, zodiacal constellations, and sometimes major planets. ...

History

Greek and Roman World

The Antikythera mechanism (main fragment)

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 Spyridon Stais discovered a lump of oxidated material with in it a mechanism with cogwheels in a shipwreck near Antikythera. This mechanism, known as the Antikythera mechanism, was dated 82 B.C. Extensive study of the fragments, using X-rays, have revealed enough details (gears, pinions, crank) [1] 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. Image File history File linksMetadata Download high resolution version (1036x924, 206 KB) Summary Principal fragment of the Antikythera mechanism. ... Image File history File linksMetadata Download high resolution version (1036x924, 206 KB) Summary Principal fragment of the Antikythera mechanism. ... The Antikythera mechanism (main fragment) The Antikythera mechanism (Greek: O μηχανισμός των Αντικυθήρων transliterated as O mÄ“chanismós tōn AntikythÄ“rōn) is an ancient mechanical analog computer (as opposed to most computers today which are digital computers) designed to calculate astronomical positions. ... The Sun is the star at the center of the Solar System. ... Apparent magnitude: up to -12. ... The eight planets and three dwarf planets of the Solar System. ... May 17 is the 137th day of the year in the Gregorian Calendar (138th in leap years). ... 1902 (MCMII) was a common year starting on Wednesday (see link for calendar). ... Wikipedia does not have an article with this exact name. ... Spur gears found on a piece of farm equipment A gear wheel is a wheel with teeth around its circumference, the purpose of the teeth being to mesh with similar teeth on another mechanical device -- possibly another gear wheel -- so that force can be transmitted between the two devices in... The Antikythera wreck is a ship wreck that was discovered by sponge divers off the coast of the Greek island, Antikythera. ... Antikythera (Αντικύθηρα) is a Greek island with a land mass of 20 square kilometers, 38 kilometers south-east of Kythira. ... The Antikythera mechanism (main fragment) The Antikythera mechanism (Greek: O μηχανισμός των Αντικυθήρων transliterated as O mÄ“chanismós tōn AntikythÄ“rōn) is an ancient mechanical analog computer (as opposed to most computers today which are digital computers) designed to calculate astronomical positions. ...

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

Middle Ages and Renaissance

The first documented astrarium clock was completed in 1364 by Giovanni de'Dondi (1318-1389), a scholar and physician of the Middle Ages interested in astronomy and horology. The original clock, consisting of 107 wheels and pinions, was lost, perhaps during the sacking of Mantua in 1630, but de'Dondi left detailed descriptions which have survived, enabling the reconstruction of the clock. It displays the mean time, sidereal, or star, time and the motions of the sun, moon and the five then known planets Venus, Mars, Saturn, Mercury, and Jupiter. It was conceived according to a Ptolemaic conception of the solar system. De'Dondi was inspired by his father Jacopo who had designed the astronomical clock in the Piazzi dei Signori, Padua in 1344 - one of the first of its type. This article belongs in one or more categories. ... The Middle Ages formed the middle period in a traditional schematic division of European history into three ages: the classical civilization of Antiquity, the Middle Ages, and modern times, beginning with the Renaissance. ... Horology is the study of the science and art of timekeeping devices. ... Illustration of a Gear train with a pinion shown. ... Adjectives: Venusian or (rarely) Cytherean Atmosphere Surface pressure: 9. ... Note: This article contains special characters. ... Note: This article contains special characters. ... Note: This article contains special characters. ... Adjectives: Jovian Atmosphere Surface pressure: 20–200 kPa[4] (cloud layer) Composition: ~86% H2 ~13% Helium 0. ... A medieval artists rendition of Claudius Ptolemaeus Claudius Ptolemaeus (Greek: ; c. ... Prague astronomical clock Astronomical clock in Lund Cathedral An astronomical clock is a clock with special mechanisms and dials to display the relative positions of the sun, moon, zodiacal constellations, and sometimes major planets. ...

In later ages more astraria were built. A famous example is the one built in 1774 by Eise Eisinga from Dronrijp, Friesland, the Netherlands. It displayed all the planets and was fixed to the ceiling in a house in Franeker where it can still be visited. Eise Jeltes Eisinga (Dronrijp, 21 February 1744 - Franeker, 27 August 1828) was a Dutch amateur astronomer who built an orrery in his house in Franeker, Netherlands. ... Franeker (Frisian: Frjentsjer) is one of the eleven cities of Friesland. ...

In modern time the astrarium grew into a tourist attraction as a commercially exploited planetarium showing in IMAX the history of the universe and other astronomical phenomena. // A planetarium is a theatre built primarily for presenting educational and entertaining shows about astronomy and the night sky, or for training in celestial navigation. ... IMAX theatre at the Melbourne Museum complex, Australia BFI London IMAX by night IMAX dome in Guayaquil, Ecuador IMAX (for Image Maximum) is a film format created by Canadas IMAX Corporation that has the capacity to display images of far greater size and resolution than conventional film display systems. ...

See also

• Astronomical clock
• Clock
• Planetarium

Prague astronomical clock Astronomical clock in Lund Cathedral An astronomical clock is a clock with special mechanisms and dials to display the relative positions of the sun, moon, zodiacal constellations, and sometimes major planets. ... A clock (from the Latin cloca, bell) is an instrument for measuring time. ... // A planetarium is a theatre built primarily for presenting educational and entertaining shows about astronomy and the night sky, or for training in celestial navigation. ...

External links

• Science and Society Picture Library: - a picture of De Dondi’s "Astrarium", the world’s first astronomical clock, 1364.
• de Dondi's Astrarium Hi-Tech, 14th Century style
• Het Eise Eisinga Planetarium
• Solar tempometer An astrarium clock running to the sun.

Literature

• Giovanni de Dondi - "Tractatus astarii"