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Octaeteris
In astronomy, an octaeteris (, plural: octaeterides) is the period of eight solar years after which the moon phase occurs on the same day of the year plus one or two days. This period is also in a very good synchronicity with five Venusian visibility cycles (the Venusian synodic period) and thirteen Venusian revolutions around the Sun (Venusian sidereal period). This means, that if Venus is visible beside the Moon, after eight years the two will be again close together near the same date of the calendar. : The octaeteris, also known as ''oktaeteris'', was noted by Cleostratus in ancient Greece as a day cycle. The octaeteris is the calendar used for the Olympic games; if one Olympiad was 50 months long, the next would be 49 lunar months long. This octaeteris calendar is used for the Olympic dial of the Antikythera mechanism, to determine the time of the Olympic games and other Greek festivities. The 8 year short lunisolar cycle was probably known to many ancien ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cleostratus
Cleostratus (; b. c. 520 BC; d. possibly 432 BC) was an astronomer of ancient Greece. He was a native of Tenedos. He is believed by ancient historians to have introduced the zodiac (beginning with Aries and Sagittarius) and the solar calendar. According to J. Webb, Cleostratus took his ideas from the Babylonians. There is little primary material to credit any person with the creation or design of the Zodiac. Historical research into this has shown translation issues and coincidences including the Tenedos connection with the Philosopher Thales. Historical writings also refer to Cleostratus as a means of establishing a tradition of authority of Greek accomplishments. Continuation of Babylonian cycles is considered not to be scientific progress as the Greeks improved the accuracy of their cycles, only exercises in the art of combining days, months, and years, of which the relative mean durations had been learned from Babylon. The Greeks may have established a similar system, as ot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astronomy
Astronomy is a natural science that studies celestial objects and the phenomena that occur in the cosmos. It uses mathematics, physics, and chemistry in order to explain their origin and their overall evolution. Objects of interest include planets, natural satellite, moons, stars, nebulae, galaxy, galaxies, meteoroids, asteroids, and comets. Relevant phenomena include supernova explosions, gamma ray bursts, quasars, blazars, pulsars, and cosmic microwave background radiation. More generally, astronomy studies everything that originates beyond atmosphere of Earth, Earth's atmosphere. Cosmology is a branch of astronomy that studies the universe as a whole. Astronomy is one of the oldest natural sciences. The early civilizations in recorded history made methodical observations of the night sky. These include the Egyptian astronomy, Egyptians, Babylonian astronomy, Babylonians, Greek astronomy, Greeks, Indian astronomy, Indians, Chinese astronomy, Chinese, Maya civilization, M ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ancient Greek Astronomy
Ancient Greek astronomy is the astronomy written in the Greek language during classical antiquity. Greek astronomy is understood to include the Ancient Greece, Ancient Greek, Hellenistic period, Hellenistic, Roman Empire, Greco-Roman, and Late antiquity, late antique eras. Ancient Greek astronomy can be divided into three phases, with ''Classical Greek astronomy'' being practiced during the 5th and 4th centuries BC, ''Hellenistic period, Hellenistic astronomy'' from the 3rd century BC until the formation of the Roman Empire in the late 1st century BC, and ''Greco-Roman astronomy'' continuing the tradition in the Roman world. During the Hellenistic era and onwards, Greek astronomy expanded beyond the geographic region of Greece as the Greek language had become the language of scholarship throughout the Hellenistic world, in large part delimited by the boundaries of the Macedonian Empire established by Alexander the Great. The most prominent and influential practitione ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eclipse Cycle
Eclipses may occur repeatedly, separated by certain intervals of time: these intervals are called eclipse cycles. The series of eclipses separated by a repeat of one of these intervals is called an eclipse series. Eclipse conditions Eclipses may occur when Earth and the Moon are aligned with the Sun, and the shadow of one body projected by the Sun falls on the other. So at new moon, when the Moon is in conjunction (astronomy), conjunction with the Sun, the Moon may pass in front of the Sun as viewed from a narrow region on the surface of Earth and cause a solar eclipse. At full moon, when the Moon is in Astronomical opposition, opposition to the Sun, the Moon may pass through the shadow of Earth, and a lunar eclipse is visible from the night half of Earth. The conjunction and opposition of the Moon together have a special name: syzygy (astronomy), syzygy (Greek language, Greek for "junction"), because of the importance of these lunar phases. An eclipse does not occur at every ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metonic Cycle
The Metonic cycle or enneadecaeteris (from , from ἐννεακαίδεκα, "nineteen") is a period of almost exactly 19 years after which the lunar phases recur at the same time of the year. The recurrence is not perfect, and by precise observation the Metonic cycle defined as 235 synodic months is just 2 hours, 4 minutes and 58 seconds longer than 19 tropical years. Meton of Athens, in the 5th century BC, judged the cycle to be a whole number of days, 6,940. Using these whole numbers facilitates the construction of a lunisolar calendar. A tropical year (about 365.24 days) is longer than 12 lunar months (about 354.36 days) and shorter than 13 of them (about 383.90 days). In a Metonic calendar (a type of lunisolar calendar), there are twelve years of 12 lunar months and seven years of 13 lunar months. Application in traditional calendars In the Babylonian and Hebrew lunisolar calendars, the years 3, 6, 8, 11, 14, 17, and 19 are the long (13-month) years of the Metonic c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Utah
Utah is a landlocked state in the Mountain states, Mountain West subregion of the Western United States. It is one of the Four Corners states, sharing a border with Arizona, Colorado, and New Mexico. It also borders Wyoming to the northeast, Idaho to the north, and Nevada to the west. In comparison to all the U.S. states and territories, Utah, with a population of just over three million, is the List of U.S. states and territories by area, 13th largest by area, the List of U.S. states and territories by population, 30th most populous, and the List of U.S. states by population density, 11th least densely populated. Urban development is mostly concentrated in two regions: the Wasatch Front in the north-central part of the state, which includes the state capital, Salt Lake City, and is home to roughly two-thirds of the population; and Washington County, Utah, Washington County in the southwest, which has approximately 180,000 residents. Most of the western half of Utah lies in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antikythera Mechanism
The Antikythera mechanism ( , ) is an Ancient Greece, Ancient Greek hand-powered orrery (model of the Solar System). It is the oldest known example of an Analog computer, analogue computer. It could be 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 similar to an Olympiad, the cycle of the ancient Olympic Games. The artefact was among wreckage retrieved from Antikythera wreck, a shipwreck off the coast of the Greek island Antikythera in 1901. In 1902, during a visit to the National Archaeological Museum, Athens, National Archaeological Museum in Athens, it was noticed by Greek politician Spyridon Stais as containing a gear, prompting the first study of the fragment by his cousin, Valerios Stais, the museum director. 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 ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Olympiad
An olympiad (, ''Olympiás'') is a period of four years, particularly those associated with the Ancient Olympic Games, ancient and Olympic Games, modern Olympic Games. Although the ancient Olympics were established during Archaic Greece, Greece's Archaic Era, it was not until Hippias of Elis, Hippias that a consistent list was established and not until Ephorus of Cyme, Ephorus in the Hellenistic period that the first recorded Olympic contest was used as a Epoch (reference date), calendar epoch. Ancient authors agreed that other Olympics had been held before the race won by Coroebus of Elis, Coroebus but disagreed on how many; the convention was established to place Coroebus's victory at a time equivalent to the summer of 776 BC, 776 BC in the Proleptic Julian calendar, and to treat it as Year 1 of Olympiad 1. Olympiad 2 began with the next games in the summer of 772 BC. Thus, for N less than 195, Olympiad N is reckoned as having started in the year 780-(4\times N) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ancient Olympic Games
The ancient Olympic Games (, ''ta Olympia''.), or the ancient Olympics, were a series of Athletics (sport), athletic competitions among representatives of polis, city-states and one of the Panhellenic Games of ancient Greece. They were held at the Panhellenic sanctuary, Panhellenic religious sanctuary of Olympia, Greece, Olympia, in honor of Zeus, and the Greeks gave them a aition, mythological origin. The originating Olympic Games are traditionally dated to 776 BC. The games were held every four years, or Olympiad, which became a unit of time in historical chronologies. These Olympiads were referred to based on the winner of their ''Stadion (running race), stadion'' sprint, e.g., "the third year of the eighteenth Olympiad when Ladas of Argos won the ''stadion''". They continued to be celebrated when Greece came under Greece in the Roman era, Roman rule in the 2nd century BC. Their last recorded celebration was in AD 393, under the emperor Theodosius I, but archaeological evidenc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ancient Greece
Ancient Greece () was a northeastern Mediterranean civilization, existing from the Greek Dark Ages of the 12th–9th centuries BC to the end of classical antiquity (), that comprised a loose collection of culturally and linguistically related city-states and communities. Prior to the Roman period, most of these regions were officially unified only once under the Kingdom of Macedon from 338 to 323 BC. In Western history, the era of classical antiquity was immediately followed by the Early Middle Ages and the Byzantine period. Three centuries after the decline of Mycenaean Greece during the Bronze Age collapse, Greek urban poleis began to form in the 8th century BC, ushering in the Archaic period and the colonization of the Mediterranean Basin. This was followed by the age of Classical Greece, from the Greco-Persian Wars to the death of Alexander the Great in 323 BC, and which included the Golden Age of Athens and the Peloponnesian War. The u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sidereal Month
In lunar calendars, a lunar month is the time between two successive syzygies of the same type: new moons or full moons. The precise definition varies, especially for the beginning of the month. Variations In Shona, Middle Eastern, and European traditions, the month starts when the young crescent moon first becomes visible, at evening, after conjunction with the Sun one or two days before that evening (e.g., in the Islamic calendar). In ancient Egypt, the lunar month began on the day when the waning moon could no longer be seen just before sunrise. Others run from full moon to full moon. Yet others use calculation, of varying degrees of sophistication, for example, the Hebrew calendar, the Chinese calendar, or the ecclesiastical lunar calendar. Calendars count integer days, so months may be 29 or 30 days in length, in some regular or irregular sequence. Lunar cycles are prominent, and calculated with great precision in the ancient Hindu Panchangam calendar, widely use ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solar 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 – as viewed from the Earth or another celestial body of the Solar System – thus completing a full cycle of astronomical seasons. For example, it is the time from vernal equinox to the next vernal equinox, or from summer solstice to the next summer solstice. It is the type of year used by tropical solar calendars. The tropical 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 G ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
