Cleostratus ( el, Κλεόστρατος; b. c. 520 BC; d. possibly 432 BC) was an

astronomer An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, moons, comets and galaxies – in either ...

ancient Greece Ancient Greece ( el, Ἑλλάς, Hellás) was a northeastern Mediterranean civilization, existing from the Greek Dark Ages of the 12th–9th centuries BC to the end of classical antiquity ( AD 600), that comprised a loose collection of cu ...

. He was a native of

Tenedos Tenedos (, ''Tenedhos'', ), or Bozcaada in Turkish, is an island of Turkey in the northeastern part of the Aegean Sea. Administratively, the island constitutes the Bozcaada district of Çanakkale Province. With an area of it is the third l ...

. He is believed by ancient historians to have introduced the

zodiac The zodiac is a belt-shaped region of the sky that extends approximately 8° north or south (as measured in celestial latitude) of the ecliptic, the apparent path of the Sun across the celestial sphere over the course of the year. The pa ...

(beginning with Aries and Sagittarius) and the

solar calendar A solar calendar is a calendar whose dates indicate the season or almost equivalently the apparent position of the Sun relative to the stars. The Gregorian calendar, widely accepted as a standard in the world, is an example of a 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 Gaius Plinius Secundus (AD 23/2479), called Pliny the Elder (), was a Roman author, naturalist and natural philosopher, and naval and army commander of the early Roman Empire, and a friend of the emperor Vespasian. He wrote the encyclopedic ' ...

in his '' Natural History'' mentioned the zodiacal circle and commented: "

Anaximander Anaximander (; grc-gre, Ἀναξίμανδρος ''Anaximandros''; ) was a pre-Socratic Greek philosopher who lived in Miletus,"Anaximander" in ''Chambers's Encyclopædia''. London: George Newnes, 1961, Vol. 1, p. 403. a city of Ionia (in mo ...

the Milesian, in the 58th

Olympiad An olympiad ( el, Ὀλυμπιάς, ''Olympiás'') is a period of four years, particularly those associated with the ancient and modern Olympic Games. Although the ancient Olympics were established during Greece's Archaic Era, it was not unti ...

, 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. Xenophanes - LROC - WAC

Censorinus Censorinus was a Roman grammarian and miscellaneous writer from the 3rd century AD. Biography He was the author of a lost work ''De Accentibus'' and of an extant treatise ''De Die Natali'', written in 238, and dedicated to his patron Quintus C ...

(''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 Harpalus (Greek: Ἅρπαλος) son of Machatas was an aristocrat of Macedon and boyhood friend of Alexander the Great in the 4th century BC. Harpalus was repeatedly entrusted with official roles by Alexander and absconded three times with la ...

.Pfundstein, James M. "....: Aeschylus, Astronomy and The Agamemnon." Classical Journal 98, no. 4 (April 2003): 397-410. The octaeteris was used before the

Metonic cycle The Metonic cycle or enneadecaeteris (from grc, ἐννεακαιδεκαετηρίς, 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 rec ...

of 19 years, and was popularly attributed to Eudoxus.

Theophrastus Theophrastus (; grc-gre, Θεόφραστος ; c. 371c. 287 BC), a Greek philosopher and the successor to Aristotle in the Peripatetic school. He was a native of Eresos in Lesbos.Gavin Hardy and Laurence Totelin, ''Ancient Botany'', Routle ...

(''de Sign. Pluv''., p. 239, ed. Basil. 1541) mentions him as a meteorological observer along with of

Methymna Mithymna () ( el, Μήθυμνα, also sometimes spelled ''Methymna'') is a town and former municipality on the island of Lesbos, North Aegean, Greece. Since the 2019 local government reform it is part of the municipality of West Lesbos, of wh ...

and Phaeinus of

Athens Athens ( ; el, Αθήνα, Athína ; grc, Ἀθῆναι, Athênai (pl.) ) is both the capital and largest city of Greece. With a population close to four million, it is also the seventh largest city in the European Union. Athens dominates a ...

Gaius Julius Hyginus Gaius Julius Hyginus (; 64 BC – AD 17) was a Latin author, a pupil of the scholar Alexander Polyhistor, and a freedman of Caesar Augustus. He was elected superintendent of the Palatine library by Augustus according to Suetonius' ''De Gramma ...

(''Poetica Astronomica'', ii. 13) says that Cleostratus first pointed out the two stars in

Auriga AURIGA (''Antenna Ultracriogenica Risonante per l'Indagine Gravitazionale Astronomica'') is an ultracryogenic resonant bar gravitational wave detector in Italy. It is at the Laboratori Nazionali di Legnaro of the Istituto Nazionale di Fisica Nuclea ...

called Haedi. The crater Cleostratus on the

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 ...

is named after him.

References

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Dictionary of Greek and Roman Biography and Mythology
{{Authority control 520s BC births 432 BC deaths People from Tenedos 5th-century BC Greek people Ancient Greek astronomers