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Astrarium
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. History Greek and Roman World 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 archaeologist named Valerios Stais discovered that a lump of oxidated material, which had been recovered from a shipwreck near the Greek island of Antikythera, held within it a mechanism with cogwheels. This mechanism, known as the Antikythera mechanism, was recently redated to end of the 2nd century BCE. Extensive study of the fragments, using X-rays, has revealed enough details (gears, pinions, crank) to enable researchers to build partial replicas of the original device. Engraved on the major gears are the names of the planets, which leaves little doubt as to the intended use of the mechanism. By t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Giovanni Dondi Dell'Orologio
Giovanni Dondi dell'Orologio (c. 1330 – 1388), also known as Giovanni de' Dondi, was an Italian physician, astronomer and mechanical engineer in Padua, now in Italy. He is remembered today as a pioneer in the art of clock design and construction. The Astrarium, which he designed and built over a period of 16 years, was a highly complex astronomical clock and planetarium, constructed only 60 or so years after the very first all-mechanical clocks had been built in Europe, and demonstrated an ambitious attempt to describe and model the planetary system with mathematical precision and technological sophistication. Life Giovanni was the second son of Jacopo Dondi dell'Orologio and Zaccarota Centrago or Centraco of Chioggia. His father was a doctor and astronomer, and builder of a large astronomical clock in the tower of the Palazzo Capitaniato of Padua in 1344. Giovanni lived with his father from 1348 to 1359, and shared his father's interest in astronomy and clockmaking. In ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astronomical Clock
An astronomical clock, horologium, or orloj is a clock with special mechanisms and dials to display astronomical information, such as the relative positions of the Sun, Moon, zodiacal constellations, and sometimes major planets. Definition The term is loosely used to refer to any clock that shows, in addition to the time of day, astronomical information. This could include the location of the Sun and Moon in the sky, the age and Lunar phases, the position of the Sun on the ecliptic and the current zodiac sign, the sidereal time, and other astronomical data such as the Moon's nodes (for indicating eclipses) or a rotating star map. The term should not be confused with ''astronomical regulator'', a high precision but otherwise ordinary pendulum clock used in observatories. Astronomical clocks usually represent the Solar System using the geocentric model. The center of the dial is often marked with a disc or sphere representing the Earth, located at the center of the Solar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gear
A gear is a rotating circular machine part having cut teeth or, in the case of a cogwheel or gearwheel, inserted teeth (called ''cogs''), which mesh with another (compatible) toothed part to transmit (convert) torque and speed. The basic principle behind the operation of gears is analogous to the basic principle of levers. A gear may also be known informally as a cog. Geared devices can change the speed, torque, and direction of a power source. Gears of different sizes produce a change in torque, creating a mechanical advantage, through their ''gear ratio'', and thus may be considered a simple machine. The rotational speeds, and the torques, of two meshing gears differ in proportion to their diameters. The teeth on the two meshing gears all have the same shape. Two or more meshing gears, working in a sequence, are called a gear train or a ''transmission''. The gears in a transmission are analogous to the wheels in a crossed, belt pulley system. An advantage of gears is t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Planetarium
A planetarium ( planetariums or ''planetaria'') is a theatre built primarily for presenting educational and entertaining shows about astronomy and the night sky, or for training in celestial navigation. A dominant feature of most planetariums is the large dome-shaped projection screen onto which scenes of stars, planets, and other celestial objects can be made to appear and move realistically to simulate their motion. The projection can be created in various ways, such as a star ball, slide projector, video, fulldome projector systems, and lasers. Typical systems can be set to simulate the sky at any point in time, past or present, and often to depict the night sky as it would appear from any point of latitude on Earth. Planetaria range in size from the 37 meter dome in St. Petersburg, Russia (called “Planetarium No 1”) to three-meter inflatable portable domes where attendees sit on the floor. The largest planetarium in the Western Hemisphere is the Jennifer Chalsty P ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jacopo Dondi Dell'Orologio
Jacopo Dondi dell'Orologio (1290–1359), also known as Jacopo de' Dondi, was a doctor, astronomer and clock-maker active in Padua, Italy. He is remembered today as a pioneer in the art of clock design and construction. He was the father of Giovanni Dondi dell'Orologio. Jacopo Dondi wrote on a number of subjects, including surgery, pharmacology, astrology and natural science. Life Jacopo Dondi was born in Chioggia, the son of a doctor named Isacco. He attended the University of Padua and was elected municipal physician in Chioggia in 1313. In about 1327 he married Zaccarota Centrago or Centraco, with whom he had eight children; the second-born child, Giovanni, became famous as the builder of the Astrarium. On 28 February 1334, Jacopo received Venetian citizenship from the Doge Francesco Dandolo. In 1342 he moved to Padova, where he became a professor of medicine and of astronomy at the University. He supervised the construction of a large public clock with a dial, commissi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antikythera Mechanism
The Antikythera mechanism ( ) is an Ancient Greek hand-powered orrery, described as the oldest example of an analogue computer used to predict astronomical positions and eclipses decades in advance. It could also be used to track the four-year cycle of athletic games which was similar to an Olympiad, the cycle of the ancient Olympic Games. This artefact was among wreckage retrieved from a shipwreck off the coast of the Greek island Antikythera in 1901. On 17 May 1902, it was identified as containing a gear by archaeologist Valerios Stais. The device, housed in the remains of a wooden-framed case of (uncertain) overall size , was found as one lump, later separated into three main fragments which are now divided into 82 separate fragments after conservation efforts. Four of these fragments contain gears, while inscriptions are found on many others. The largest gear is approximately in diameter and originally had 223 teeth. In 2008, a team led by Mike Edmunds and Tony Free ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jupiter
Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but slightly less than one-thousandth the mass of the Sun. Jupiter is the third brightest natural object in the Earth's night sky after the Moon and Venus, and it has been observed since prehistoric times. It was named after the Roman god Jupiter, the king of the gods. Jupiter is primarily composed of hydrogen, but helium constitutes one-quarter of its mass and one-tenth of its volume. It probably has a rocky core of heavier elements, but, like the other giant planets in the Solar System, it lacks a well-defined solid surface. The ongoing contraction of Jupiter's interior generates more heat than it receives from the Sun. Because of its rapid rotation, the planet's shape is an oblate spheroid: it has a slight but noticeable bulge around the equator. The outer atmospher ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ptolemy
Claudius Ptolemy (; grc-gre, Πτολεμαῖος, ; la, Claudius Ptolemaeus; AD) was a mathematician, astronomer, astrologer, geographer, and music theorist, who wrote about a dozen scientific treatises, three of which were of importance to later Byzantine, Islamic, and Western European science. The first is the astronomical treatise now known as the ''Almagest'', although it was originally entitled the ''Mathēmatikē Syntaxis'' or ''Mathematical Treatise'', and later known as ''The Greatest Treatise''. The second is the ''Geography'', which is a thorough discussion on maps and the geographic knowledge of the Greco-Roman world. The third is the astrological treatise in which he attempted to adapt horoscopic astrology to the Aristotelian natural philosophy of his day. This is sometimes known as the ''Apotelesmatika'' (lit. "On the Effects") but more commonly known as the '' Tetrábiblos'', from the Koine Greek meaning "Four Books", or by its Latin equivalent ''Qua ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eise Eisinga Planetarium
The Royal Eise Eisinga Planetarium ( nl, Koninklijk(e) Eise Eisinga Planetarium) is an 18th-century orrery in Franeker, Friesland, Netherlands. It is currently a museum and open to the public. The orrery has been on the top 100 Dutch heritage sites list since 1990 and in December 2011 was placed on a provisionary list of future UNESCO World Heritage Site candidates. It is the oldest working orrery in the world. History The orrery was built from 1774 to 1781 by Eise Eisinga, a wool comber and amateur astronomer. Eise Eisinga’s mechanical planetarium is built into the timber roof of the living room ceiling of his historic canal house. William I, Prince of Orange and the first King of the Netherlands was so impressed with the planetarium, he purchased the house and it became a royal planetarium. The museum consists of the planetarium room, a screening room where documentaries are shown, and special exhibits based on modern astronomy. Other parts on permanent display are Eising ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Padua
Padua ( ; it, Padova ; vec, Pàdova) is a city and ''comune'' in Veneto, northern Italy. Padua is on the river Bacchiglione, west of Venice. It is the capital of the province of Padua. It is also the economic and communications hub of the area. Padua's population is 214,000 (). The city is sometimes included, with Venice (Italian ''Venezia'') and Treviso, in the Padua-Treviso-Venice Metropolitan Area (PATREVE) which has a population of around 2,600,000. Padua stands on the Bacchiglione River, west of Venice and southeast of Vicenza. The Brenta River, which once ran through the city, still touches the northern districts. Its agricultural setting is the Venetian Plain (''Pianura Veneta''). To the city's south west lies the Euganaean Hills, praised by Lucan and Martial, Petrarch, Ugo Foscolo, and Shelley. Padua appears twice in the UNESCO World Heritage List: for its Botanical Garden, the most ancient of the world, and the 14th-century Frescoes, situated in d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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