Cleostratus (Greek : Κλεόστρατος; 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 other cultures had too, independently of the Babylonians. However, most agree that there can never be a definite answer for the argument concerning who established the first known system in the west.
Pliny the Elder in his Natural History mentioned the zodiacal circle and commented: "Anaximander the Milesian, in the 58th Olympiad, is said to have been the first who understood its obliquity, and thus opened the road to a correct knowledge of the subject. Afterwards Cleostratus made the signs in it, first marking those of Aries and Sagittarius; Atlas had formed the sphere long before this time."Pliny also was writing in a way similar to his contemporaries in that a sound argument had to be based on past knowledge or the accomplishments of past thinkers.
Censorinus (De Die Natali, c. 18) considers Cleostratus to have been the inventor of the octaeteris, or cycle of eight years. Cleostratus' name is associated with an eight-year intercalation cycle, to keep Greek civil calendars (lunar in nature) in line with the solar year, a cycle which was improved by Harpalus. 239, ed. Basil. 1541) mentions him as a meteorological observer along with Matricetas [ fr ] of Methymna and Phaeinus of Athens. Gaius Julius Hyginus (Poetica Astronomica, ii. 13) says that Cleostratus first pointed out the two stars in Auriga called Haedi.The octaeteris was used before the Metonic cycle of 19 years, and was popularly attributed to Eudoxus. Theophrastus (de Sign. Pluv., p.
The crater Cleostratus on the Moon is named after him.
Hipparchus of Nicaea was a Greek astronomer, geographer, and mathematician. He is considered the founder of trigonometry but is most famous for his incidental discovery of precession of the equinoxes.
Astronomy is the oldest of the natural sciences, dating back to antiquity, with its origins in the religious, mythological, cosmological, calendrical, and astrological beliefs and practices of prehistory: vestiges of these are still found in astrology, a discipline long interwoven with public and governmental astronomy. It was not completely separated in Europe during the Copernican Revolution starting in 1543. In some cultures, astronomical data was used for astrological prognostication. The study of astronomy has received financial and social support from many institutions, especially the Church, which was its largest source of support between the 12th century to the Enlightenment.
A lunar calendar is a calendar based on the monthly cycles of the Moon's phases, in contrast to solar calendars, whose annual cycles are based only directly on the solar year. The most commonly used calendar, the Gregorian calendar, is a solar calendar system that originally evolved out of a lunar calendar system. A purely lunar calendar is also distinguished from a lunisolar calendar, whose lunar months are brought into alignment with the solar year through some process of intercalation. The details of when months begin varies from calendar to calendar, with some using new, full, or crescent moons and others employing detailed calculations.
The Roman calendar was the calendar used by the Roman kingdom and republic. The term often includes the Julian calendar established by the reforms of the dictator Julius Caesar and emperor Augustus in the late 1st century BC and sometimes includes any system dated by inclusive counting towards months' kalends, nones, and ides in the Roman manner. The term usually excludes the Alexandrian calendar of Roman Egypt, which continued the unique months of that land's former calendar; the Byzantine calendar of the later Roman Empire, which usually dated the Roman months in the simple count of the ancient Greek calendars; and the Gregorian calendar, which refined the Julian system to bring it into still closer alignment with the tropical year.
The zodiac is an area of the sky that extends approximately 8° north or south of the ecliptic, the apparent path of the Sun across the celestial sphere over the course of the year. The paths of the Moon and visible planets are also within the belt of the zodiac.
Kidinnu was a Chaldean astronomer and mathematician. Strabo of Amaseia called him Kidenas, Pliny the Elder Cidenas, and Vettius Valens Kidynas.
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 34 cm × 18 cm × 9 cm wooden box, 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 13 centimetres (5.1 in) in diameter and originally had 223 teeth. In 2008, a team led by Mike Edmunds and Tony Freeth at Cardiff University used modern computer x-ray tomography and high resolution surface scanning to image inside fragments of the crust-encased mechanism and read the faintest inscriptions that once covered the outer casing of the machine. This suggests it had 37 meshing bronze gears enabling it to follow the movements of the Moon and the Sun through the zodiac, to predict eclipses and to model the irregular orbit of the Moon, where the Moon's velocity is higher in its perigee than in its apogee. This motion was studied in the 2nd century BC by astronomer Hipparchus of Rhodes, and it is speculated that he may have been consulted in the machine's construction. There is speculation that a portion of the mechanism is missing and it also calculated the positions of the five classical planets.
The Iranian calendars or Iranian chronology are a succession of calendars invented or used for over two millennia in Iran, also known as Persia. One of the longest chronological records in human history, the Iranian calendar has been modified time and again during its history to suit administrative, climatic, and religious purposes. The most influential face in laying the frameworks for the calendar and its precision was the 11 century Persian polymath, hakim Omar Khayyam. The modern Iranian calendar is currently the official calendar in Iran. It begins at the midnight nearest to the instant of the vernal equinox as determined by astronomic calculations for the Iran Standard Time meridian. It is, therefore, an observation-based calendar, unlike the Gregorian, which is rule-based.
Nabû-nāṣir was the king of Babylon from 747 to 734 BC. He deposed a foreign Chaldean usurper named Nabu-shuma-ishkun, bringing native rule back to Babylon after twenty-three years of Chaldean rule. His reign saw the beginning of a new era characterized by the systematic maintenance of chronologically precise historical records. Both the Babylonian Chronicle and the Ptolemaic Canon begin with his accession to the throne. He was contemporary with the Assyrian kings Aššur-nirarī V and Tiglath-Pileser III, the latter under whom he became a vassal, and the Elamite kings Humban-Tahrah I and Humban-Nikaš I.
The ancient Egyptian calendar – a civil calendar – was a solar calendar with a 365-day year. The year consisted of three seasons of 120 days each, plus an intercalary month of five epagomenal days treated as outside of the year proper. Each season was divided into four months of 30 days. These twelve months were initially numbered within each season but came to also be known by the names of their principal festivals. Each month was divided into three 10-day periods known as decans or decades. It has been suggested that during the Nineteenth Dynasty and the Twentieth Dynasty the last two days of each decan were usually treated as a kind of weekend for the royal craftsmen, with royal artisans free from work.
In Western astrology, astrological signs are the twelve 30 degree sectors that make up Earth's 360 degree orbit around the Sun. The signs enumerate from the first day of spring known as the First Point of Aries which is the vernal equinox. The Western astrological signs are Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius and Pisces. The Western zodiac originated in Babylonian astrology, and was later influenced by Hellenistic culture. Each sign was named after a constellation the sun annually moved through while crossing the sky. This observation is emphasized in the simplified and popular sun sign astrology. Over the centuries, Western astrology's zodiacal divisions have shifted out of alignment with the constellations they were named after by axial precession while Hindu astrology measurements correct for shifting.Astrology has developed in Chinese and Tibetan cultures as well.
Aries (♈︎) is the first astrological sign in the zodiac, spanning the first 30 degrees of celestial longitude, and originates from the constellation of the same name. Under the tropical zodiac, the Sun transits this sign from approximately March 20 to April 21 each year. This time duration is exactly the first month of the Solar Hijri calendar.
Hebrew astronomy refers to any astronomy written in Hebrew or by Hebrew speakers, or translated into Hebrew, or written by Jews in Judeo-Arabic. It includes a range of genres from the earliest astronomy and cosmology contained in the Bible, mainly the Tanakh, to Jewish religious works like the Talmud and very technical works.
The decans are 36 groups of stars used in the ancient Egyptian astronomy. They rose consecutively on the horizon throughout each earth rotation. The rising of each decan marked the beginning of a new decanal "hour" of the night for the ancient Egyptians, and they were used as a sidereal star clock beginning by at least the 9th or 10th Dynasty.
Babylonian astronomy was the study or recording of celestial objects during the early history of Mesopotamia.
Often called lunar mansion, a lunar station or lunar house is a segment of the ecliptic through which the Moon passes in its orbit around the Earth. The concept was used by several ancient cultures as part of their calendrical system. In general, though not always, the zodiac is divided into 27 or 28 segments relative to the vernal equinox point or the fixed stars – one for each day of the lunar month. The Moon's position is charted with respect to those fixed segments. Since the Moon's position at any given stage will vary according to Earth's position in its own orbit, lunar stations are an effective system for keeping track of the passage of seasons.
The eclipse of Thales was a solar eclipse that was, according to The Histories of Herodotus, accurately predicted by the Greek philosopher Thales of Miletus. If Herodotus's account is accurate, this eclipse is the earliest recorded as being known in advance of its occurrence. Many historians believe that the predicted eclipse was the solar eclipse of 28 May 585 BC. How exactly Thales predicted the eclipse remains uncertain; some scholars assert the eclipse was never predicted at all. Others have argued for different dates, but only the eclipse of 28 May 585 BC matches the conditions of visibility necessary to explain the historical event.
Babylonian astronomy collated earlier observations and divinations into sets of Babylonian star catalogues, during and after the Kassite rule over Babylonia. These star catalogues, written in cuneiform script, contained lists of constellations, individual stars, and planets. The constellations were probably collected from various other sources. The earliest catalogue, Three Stars Each, mentions stars of Akkad, of Amurru, of Elam and others. Various sources have theorized a Sumerian origin for these Babylonian constellations, but an Elamite origin has also been proposed. A connection to the star symbology of Kassite kudurru border stones has also been claimed, but whether such kudurrus really represented constellations and astronomical information aside from the use of the symbols remains unclear.
Mesha Sankranti refers to the first day of the solar cycle year, that is the solar New Year in the Hindu luni-solar calendar. The Hindu calendar also has a lunar new year, which is religiously more significant, and falls on different dates in the Amanta and Purinamanta systems prevalent across the Indian subcontinent. The solar cycle year is significant in Assamese, Odia, Punjabi, Malayalam, Tamil, and Bengali calendars.
Dodecatemoria are subdivisions of the twelve signs of the Zodiac into a further twelve parts each. These can be said to form a "micro-zodiac" of 144 dodecatemoria, each corresponding to 2.5° of the ecliptic. In an alternate usage, the dodecamorion refers to a point on the ecliptic reached by the addition of twelve times a given number of degrees within a sign, either to the original degree, or to the beginning of the sign.