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Callippus Of Cyzicus
Callippus (; grc, Κάλλιππος; c. 370 BC – c. 300 BC) was a Greek astronomer and mathematician. Biography Callippus was born at Cyzicus, and studied under Eudoxus of Cnidus at the Academy of Plato. He also worked with Aristotle at the Lyceum, which means that he was active in Athens prior to Aristotle's death in 322 BC. He observed the movements of the planets and attempted to use Eudoxus' scheme of connected spheres to account for their movements. However, he found that 27 spheres was insufficient to account for the planetary movements, and so he added seven more for a total of 34. According to the description in Aristotle's ''Metaphysics'' (XII.8), he added two spheres for the Sun, two for the Moon, and one each for Mercury, Venus, and Mars. Callippus made careful measurements of the lengths of the seasons, finding them (starting with the spring equinox) to be 94 days, 92 days, 89 days, and 90 days. This variation in the seasons implies a variation in the speed of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Greek Astronomy
Greek astronomy is astronomy written in the Greek language in classical antiquity. Greek astronomy is understood to include the Ancient Greek, Hellenistic, Greco-Roman, and Late Antiquity eras. It is not limited geographically to Greece or to ethnic Greeks, as the Greek language had become the language of scholarship throughout the Hellenistic world following the conquests of Alexander. This phase of Greek astronomy is also known as Hellenistic astronomy, while the pre-Hellenistic phase is known as Classical Greek astronomy. During the Hellenistic and Roman periods, much of the Greek and non-Greek astronomers working in the Greek tradition studied at the Museum and the Library of Alexandria in Ptolemaic Egypt. The development of astronomy by the Greek and notably Hellenistic astronomers is considered to be a major phase in the history of astronomy. Greek astronomy is characterized by seeking a geometrical model for celestial phenomena. Most of the names of the stars, planets, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tropical Year
A tropical year or solar year (or tropical period) is the time that the Sun takes to return to the same position in the sky of a celestial body of the Solar System such as the Earth, completing a full cycle of seasons; for example, the time from vernal equinox to vernal equinox, or from summer solstice to summer solstice. It is the type of year used by tropical solar calendars. The solar year is one type of astronomical year and particular orbital period. Another type is the sidereal year (or sidereal orbital period), which is the time it takes Earth to complete one full orbit around the Sun as measured with respect to the fixed stars, resulting in a duration of 20 minutes longer than the tropical year, because of the precession of the equinoxes. Since antiquity, astronomers have progressively refined the definition of the tropical year. The entry for "year, tropical" in the '' Astronomical Almanac Online Glossary'' states: An equivalent, more descriptive, definition is "The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
370s BC Births
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37 may refer to: * 37 (number), the natural number following 36 and preceding 38 Years * 37 BC * AD 37 * 1937 * 2037 Other uses * ''37'' (album), by King Never, 2013 * ''37'' (film), a 2016 film about the murder of Kitty Genovese * 37 (MBTA bus), a bus route in Boston, Massachusetts, US * 37 (New Jersey bus), a NJ Transit bus route in New Jersey, US * "Thirty Seven", a song by Karma to Burn from the album ''Almost Heathen'', 2001 See also * 37th (other) * List of highways numbered 37 The following highways are numbered 37: Australia * Newcastle Inner City Bypass * Nubeena Road (TAS) Canada * Alberta Highway 37 * British Columbia Highway 37 * Winnipeg Route 37 * Ontario Highway 37 * Saskatchewan Highway 37 * Yukon Highway 37 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aristotelian Philosophers
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Aristotelian may refer to: * Aristotle (384–322 BCE), Greek philosopher * Aristotelianism, the philosophical tradition begun by Aristotle * Aristotelian ethics * Aristotelian logic, term logic * Aristotelian physics, the natural sciences * Aristotelian Society, founded at a meeting on 19 April 1880 * Aristotelian theology * Aristotelian tragedy Tragedy (from the grc-gre, τραγῳδία, ''tragōidia'', ''tragōidia'') is a genre of drama based on human suffering and, mainly, the terrible or sorrowful events that befall a main character. Traditionally, the intention of tragedy i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ancient Greek Mathematicians
Greek mathematics refers to mathematics texts and ideas stemming from the Archaic through the Hellenistic and Roman periods, mostly extant from the 7th century BC to the 4th century AD, around the shores of the Eastern Mediterranean. Greek mathematicians lived in cities spread over the entire Eastern Mediterranean from Italy to North Africa but were united by Greek culture and the Greek language. The word "mathematics" itself derives from the grc, , máthēma , meaning "subject of instruction". The study of mathematics for its own sake and the use of generalized mathematical theories and proofs is an important difference between Greek mathematics and those of preceding civilizations. Origins of Greek mathematics The origin of Greek mathematics is not well documented. The earliest advanced civilizations in Greece and in Europe were the Minoan and later Mycenaean civilizations, both of which flourished during the 2nd millennium BCE. While these civilizations possessed writing an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ancient Greek Astronomers
Ancient history is a time period from the beginning of writing and recorded human history to as far as late antiquity. The span of recorded history is roughly 5,000 years, beginning with the Sumerian cuneiform script. Ancient history covers all continents inhabited by humans in the period 3000 BCAD 500. The three-age system periodizes ancient history into the Stone Age, the Bronze Age, and the Iron Age, with recorded history generally considered to begin with the Bronze Age. The start and end of the three ages varies between world regions. In many regions the Bronze Age is generally considered to begin a few centuries prior to 3000 BC, while the end of the Iron Age varies from the early first millennium BC in some regions to the late first millennium AD in others. During the time period of ancient history, the world population was already exponentially increasing due to the Neolithic Revolution, which was in full progress. While in 10,000 BC, the world population stood at ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
4th-century BC Greek People
The 4th century (per the Julian calendar and Anno Domini/Common era) was the time period which lasted from 301 ( CCCI) through 400 ( CD). In the West, the early part of the century was shaped by Constantine the Great, who became the first Roman emperor to adopt Christianity. Gaining sole reign of the empire, he is also noted for re-establishing a single imperial capital, choosing the site of ancient Byzantium in 330 (over the current capitals, which had effectively been changed by Diocletian's reforms to Milan in the West, and Nicomedeia in the East) to build the city soon called Nova Roma (New Rome); it was later renamed Constantinople in his honor. The last emperor to control both the eastern and western halves of the empire was Theodosius I. As the century progressed after his death, it became increasingly apparent that the empire had changed in many ways since the time of Augustus. The two emperor system originally established by Diocletian in the previous century fell in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Moon
The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of Australia). The Moon is a planetary-mass object with a differentiated rocky body, making it a satellite planet under the geophysical definitions of the term and larger than all known dwarf planets of the Solar System. It lacks any significant atmosphere, hydrosphere, or magnetic field. Its surface gravity is about one-sixth of Earth's at , with Jupiter's moon Io being the only satellite in the Solar System known to have a higher surface gravity and density. The Moon orbits Earth at an average distance of , or about 30 times Earth's diameter. Its gravitational influence is the main driver of Earth's tides and very slowly lengthens Earth's day. The Moon's orbit around Earth has a sidereal period of 27.3 days. During each synodic period ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Calippus (crater)
Calippus is a small lunar impact crater that is located on the eastern edge of the rugged Montes Caucasus mountain range in the northern part of the Moon. It was named after Greek astronomer Callippus of Cyzicus. It lies to the southwest of the crater remnant Alexander, to the northwest of the Mare Serenitatis. The outer rim of Calippus has an irregular appearance, with outward bulges to the northeast and particularly to the west where there is an interior shelf of slumped material. The exterior has a slight rampart that is surrounded by the rugged terrain of the mountain range. Within the sharp-sided interior walls is a rough and irregular interior floor. To the southeast of this crater, on the edge of the Mare Serenitatis, is an arcing rille Rille (German for 'groove') is typically used to describe any of the long, narrow depressions in the surface of the Moon that resemble channels. The Latin term is ''rima'', plural ''rimae''. Typically, a rille can be several kilom ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antikythera Mechanism
The Antikythera mechanism ( ) is an Ancient Greece, Ancient Greek hand-powered orrery, described as the oldest example of an analogue computer used to predict astronomy, 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 Antikythera wreck, 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, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proleptic Julian Calendar
The proleptic Julian calendar is produced by extending the Julian calendar backwards to dates preceding AD 8 when the quadrennial leap year stabilized. The leap years that were actually observed between the implementation of the Julian calendar in 45 BC and AD 8 were erratic (see the Julian calendar article for details). A calendar obtained by extension earlier in time than its invention or implementation is called the " proleptic" version of the calendar. Likewise, the proleptic Gregorian calendar is occasionally used to specify dates before the introduction of the Gregorian calendar in 1582. Because the Julian calendar was used before that time, one must explicitly state that a given quoted date is based on the proleptic Gregorian calendar if that is the case. The Julian calendar itself was introduced by Julius Caesar, and as such is older than the introduction of the Anno Domini era (or the "Common Era"), counting years since the birth of Christ as calculated by Dionysus Exig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Callippic Cycle
The Callippic cycle (or Calippic) is a particular approximate common multiple of the tropical year and the synodic month, proposed by Callippus in 330 BC. It is a period of 76 years, as an improvement of the 19-year Metonic cycle. Description A century before Callippus, Meton had described a cycle in which 19 years equals 235 lunations. If we assume a year is about days, 19 years total about 6,940 days, which exceeds 235 lunations by almost a third of a day, and 19 tropical years by four tenths of a day. It implicitly gave the solar year a duration of = 365 + = 365 + + days = 365 d 6 h 18 min 56 s. Callippus accepted the 19-year cycle, but held that the duration of the year was more closely days (= 365 d 6 h), so he multiplied the 19-year cycle by 4 to obtain an integer number of days, and then omitted 1 day from the last 19-year cycle. Thus, he computed a cycle of 76 years that consists of 940 lunations and 27,759 days, which has been named the ''Callippic'' cycle after him. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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