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Meton
Meton of Athens (; ''gen''.: Μέτωνος) was a Greek mathematician, astronomer, geometer, and engineer who lived in Athens in the 5th century BC. He is best known for calculations involving the eponymous 19-year Metonic cycle, which he introduced in 432 BC into the lunisolar Attic calendar. Euphronios says that Colonus was Meton's deme. Work The Metonic calendar incorporates knowledge that 19 solar years and 235 lunar months are very nearly of the same duration. Consequently, a given day of a lunar month will often occur on the same day of the solar year as it did 19 years previously. Meton's observations were made in collaboration with Euctemon, about whom nothing else is known. The Greek astronomer Callippus expanded on the work of Meton, proposing what is now called the Callippic cycle. A Callippic cycle runs for 76 years, or four Metonic cycles. Callippus refined the lunisolar calendar, deducting one day from the fourth Metonic cycle in each Callippic cycle (i.e., ... [...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] |
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] |
Callippus
Callippus (; ; 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 were 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 the Sun, called the "sol ... [...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, and judged it to be 6,940 days. This 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. The cycle's error has been comput ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lunisolar Calendar
A lunisolar calendar is a calendar in many cultures, that combines monthly lunar cycles with the solar year. As with all calendars which divide the year into months, there is an additional requirement that the year have a whole number of months (Moon cycles). The majority of years have twelve months but every second or third year is an embolismic year, which adds a thirteenth intercalary, embolismic, or leap month. Lunisolar calendars are lunar calendars but, in contrast to purely lunar calendars such as the Islamic calendar, have additional intercalation rules that reset them periodically into a rough agreement with the solar year and thus with the seasons. Examples The Chinese, Buddhist, Burmese, Assyrian, Hebrew, Jain, traditional Nepali, Hindu, Japanese, Korean, Mongolian, Tibetan, and Vietnamese calendars (in the East Asian Chinese cultural sphere), plus the ancient Hellenic, Coligny, and Babylonian calendars are all lunisolar. Also, some of the ancient pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The Birds (play)
''The Birds'' () is a comedy by the Ancient Greek playwright Aristophanes. It was performed in 414 BC at the City Dionysia in Athens where it won second place. It has been acclaimed by modern critics as a perfectly realized fantasy remarkable for its mimicry of birds and for the gaiety of its songs. Unlike the author's other early plays, it includes no direct mention of the Peloponnesian War and there are few references to Athenian politics, and yet it was staged not long after the commencement of the Sicilian Expedition, an ambitious military campaign that greatly increased Athenian commitment to the war effort. In spite of that, the play has many indirect references to Athenian political and social life. It is the longest of Aristophanes's surviving plays and yet it is a fairly conventional example of Old Comedy. The plot of the play revolves around Pisthetaerus, an Athenian who convinces the birds to create a great city in the sky, and thus regain their status as the original ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Attic Calendar
The Attic calendar or Athenian calendar is the lunisolar calendar beginning in midsummer with the lunar month of Hekatombaion, in use in ancient Attica, the ancestral territory of the Athenian polis. It is sometimes called the Greek calendar because of Athens's cultural importance, but it is only one of many ancient Greek calendars. Although relatively abundant, the evidence for the Attic calendar is still patchy and often contested. As it was well known in Athens and of little use outside Attica, no contemporary source set out to describe the system as a whole. Further, even during the well-sourced 5th and 4th centuries BC, the calendar underwent changes, not all perfectly understood. As such, any account given of it must be a tentative reconstruction. Local focus The Attic calendar was an exclusively local phenomenon, used to regulate the internal affairs of the Athenians, with little relevance to the outside world. For example, just across the border in Boeotia, the months h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Euctemon
Euctemon (, ''gen.'' Εὐκτήμωνος; fl. 432 BC) was an Athenian astronomer. He was a contemporary of Meton and worked closely with this astronomer. Little is known of his work apart from his partnership with Meton and what is mentioned by Ptolemy. With Meton, he made a series of observations of the solstices (the points at which the Sun is seen at the greatest distance from the equator) in order to determine the length of the tropical year. Geminus and Ptolemy quote him as a source on the rising and setting of the stars. Pausanias's ''Description of Greece'' names Damon and Philogenes as Euctemon's children. The lunar crater Lunar craters are impact craters on Earth's Moon. The Moon's surface has many craters, all of which were formed by impacts. The International Astronomical Union currently recognizes 9,137 craters, of which 1,675 have been dated. History The wo ... Euctemon is named after him. References External links *Greek Astronomy 5th-century BC At ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pnyx
The Pnyx (; ; , ''Pnyka'') is a hill or hillside in central Athens, the capital of Greece. Beginning as early as 507 BC (Fifth-century Athens), the Athenians gathered on the Pnyx to host their popular assemblies, thus making the hill one of the earliest and most important sites in the creation of democracy. The Pnyx is located less than west of the Acropolis and about 2 km south-west of the Syntagma Square in the centre of Athens. The "mainly natural hollow" was first used from before 500 BC to perhaps 404 BC, when the arrangement was changed by adding a retaining wall below the speakers' platform, with the space between filled with earth. The Pnyx was probably the prototype for the Greek theatre auditorium, with the late form perhaps reflecting changes in theatre design. Historical significance The Pnyx was used for popular assemblies in Athens as early as 507 BC, when the reforms of Cleisthenes transferred political power to the citizenry. It was then outside the city prope ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brackets
A bracket is either of two tall fore- or back-facing punctuation marks commonly used to isolate a segment of text or data from its surroundings. They come in four main pairs of shapes, as given in the box to the right, which also gives their names, that vary between British English, British and American English. "Brackets", without further qualification, are in British English the ... marks and in American English the ... marks. Other symbols are repurposed as brackets in specialist contexts, such as International Phonetic Alphabet#Brackets and transcription delimiters, those used by linguists. Brackets are typically deployed in symmetric pairs, and an individual bracket may be identified as a "left" or "right" bracket or, alternatively, an "opening bracket" or "closing bracket", respectively, depending on the Writing system#Directionality, directionality of the context. In casual writing and in technical fields such as computing or linguistic analysis of grammar, brackets ne ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Winter Solstice
The winter solstice, or hibernal solstice, occurs when either of Earth's geographical pole, poles reaches its maximum axial tilt, tilt away from the Sun. This happens twice yearly, once in each hemisphere (Northern Hemisphere, Northern and Southern Hemisphere, Southern). For that hemisphere, the winter solstice is the day with the shortest daytime, period of daylight and longest night of the year, and when the Sun is at its lowest culmination, daily maximum elevation in the sky. Each Polar Circle, polar region experiences polar night, continuous darkness or twilight around its winter solstice. The opposite event is the summer solstice. The winter solstice occurs during the hemisphere's winter. In the Northern Hemisphere, this is the December solstice (December 21 or 22) and in the Southern Hemisphere, this is the June solstice (June 20 or 21). Although the winter solstice itself lasts only a moment, the term also refers to the day on which it occurs. Traditionally, in many Tem ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
