What is "hipparchus"

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.

Hipparchus was born in Nicaea, Bithynia (now Iznik, Turkey), and probably died on the island of Rhodes. He is known to have been a working astronomer at least from 162 to 127 . Hipparchus is considered the greatest ancient astronomical observer and, by some, the greatest overall astronomer of antiquity. He was the first whose quantitative and accurate models for the motion of the Sun and Moon survive. For this he certainly made use of the observations and perhaps the mathematical techniques accumulated over centuries by the Babylonians and other people from Mesopotamia. He developed trigonometry and constructed trigonometric tables, and he solved several problems of spherical trigonometry. With his solar and lunar theories and his trigonometry, he may have been the first to develop a reliable method to predict solar eclipses. His other reputed achievements include the discovery and measurement of Earth's precession, the compilation of the first comprehensive star catalog of the western world, and possibly the invention of the astrolabe, also of the armillary sphere, which he used during the creation of much of the star catalogue. It would be three centuries before Claudius Ptolemaeus' synthesis of astronomy would supersede the work of Hipparchus.

Hipparchus or Hipparch (; died 514 BC) was a member of the ruling class of Athens. He was one of the sons of Peisistratos.

He was said by some Greek authors to have been the tyrant of Athens along with his brother Hippias after Peisistratos died, about 528/7 BC. The word tyrant literally means "one who takes power by force", as opposed to a ruler who inherited a monarchy or was chosen in some way. It carried no pejorative connotation during the Archaic and early Classical periods. In actuality, according to Thucydides, Hippias was the only 'tyrant'. Both Hipparchus and Hippias enjoyed the popular support of the people. Hipparchus was a patron of the arts; it was Hipparchus who invited Simonides of Ceos to Athens.

In 514 BC Hipparchus was assassinated by the Tyrannicides, Harmodius and Aristogeiton. This was apparently a personal dispute, according to Herodotus and Thucydides. Hipparchus had fallen in love with Harmodius, who was already the lover of Aristogeiton. Not only did Harmodius reject him, but humiliated him by telling Aristogeiton of his advances. Hipparchus then invited Harmodius' sister to participate in the Panathenaic Festival as kanephoros only to publicly disqualify her on the grounds that she was not a virgin. Harmodius and Aristogeiton then organised a revolt for the Panathenaic Games but they panicked and attacked too early. Although they killed Hipparchus, Harmodius was killed by his bodyguard and Aristogeiton was arrested, tortured and later killed. According to Thucydides, Hippias ordered the Greeks to lay down their ceremonial arms and then had them searched, arresting any found with concealed weapons. This was later denied by Aristotle, who said that this story was created by the democratic government in order to impress upon the people how much of a tyrant Hippias was. Aristotle also mentions that Aristogeiton was tortured in order to give the names of the conspirators in the plot. Enraged that Hippias hadn't killed him, Aristogeiton offered more names to Hippias in exchange for his hand in pledge. When Hippias put his hand on Aristogeiton's, Aristogeiton berated him for giving his hand to his brother's murderer — at which point Hippias stabbed Aristogeiton in rage.

After the assassination, Hippias became a bitter and cruel tyrant, and was overthrown a few years later in 510 by the Spartan king Cleomenes I. Some modern scholars generally ascribes the tradition that Hipparchus was himself a cruel tyrant to the cult of Harmodius and Aristogeiton established after the downfall of the tyranny; however, others have advanced the theory that the cult of the tyrannicides was a propaganda coup of the early democratic government to obscure the Spartan involvement in the regime change.

Hipparchus is the namesake and topic of discussion in one of Plato's shorter dialogues, in which Socrates and an unnamed companion attempt to define philokerdes (love of gain).

A hipparchus or hipparch ( hipparkhos) was the title of an ancient Greek cavalry officer, commanding a hipparchia (unit of about 500 horsemen); two such units were commanded by an epihipparchos.

Category:Ancient Greek military terminology Category:Military ranks of ancient Greece Category:Military ranks of ancient Macedon

Hipparchus Crater is an impact crater in the Phaethontis quadrangle of Mars, located at 44.8° S latitude and 151.4° W longitude. It is 93.0 km in diameter and was named after Hipparchus, and the name was approved in 1973.

Hipparchus is the degraded remnant of a lunar crater. It is located to the southeast of Sinus Medii, near the center of the visible Moon. To the south is the prominent crater Albategnius, and to the southwest lies Ptolemaeus, a feature of comparable dimensions to Hipparchus. Horrocks lies entirely within the northeast rim of the crater. Halley is attached to the south rim, and Hind lies to the southeast. To the north-northeast is the bowl-shaped Pickering, and the flooded Saunder is located off the northeast rim.

High-resolution images of Hipparchus were obtained by Lunar Orbiter 5 in 1967.

Hipparchus, the common Latinization of the Greek Hipparkhos, can mean:

• Hipparchus, the ancient Greek astronomer
  • Hipparchic cycle, an astronomical cycle he created
  • Hipparchus (lunar crater), a lunar crater named in his honour
  • Hipparchus (Martian crater), a crater on Mars named in his honour
  • 4000 Hipparchus, an asteroid named in his honour
  • Hipparcos, an astrometry space mission named in his honour
• Hipparchus (cavalry officer), commander of one hipparchia
  • Epihipparch, commander of two hipparchiai
• Hipparchus (son of Pisistratus), an ancient Athenian tyrant
• Hipparchus of Euboea, an ancient Euboean tyrant
• Hipparchus (poet), an ancient Greek actor from Corinth
• Tiberius Claudius Hipparchus Marathonios, the richest man in the Roman Empire in the 1st century BC
• Hipparchus (dialogue), a dialogue ascribed to Plato

The Hipparchus (; ), or Hipparch, is a dialogue attributed to the classical Greek philosopher and writer Plato. There is some debate as to the work's authenticity. Stylistically, the dialogue bears many similarities to the Minos. They are the only dialogues between Socrates and a single anonymous companion; they are the only dialogues where the titles bear the name of someone long-dead; and they are the only dialogues which begin with Socrates raising a "what is" question.

The primary aim of the dialogue is an attempt to define greed. A friend of Socrates argues that greed is a desire to profit from things of no value, but Socrates replies that no sensible man attempts to profit from worthless things, but inasfar as greed is a desire for profit, then it is a desire for the good, and thus everyone is greedy. The friend of Socrates thinks there is something wrong with Socrates' argument, but cannot say what is wrong with it.

In the dialogue Socrates discusses Hipparchus, a tyrant of the 6th century BC. Thus there is another theme in the dialogue concerning intellectual honesty and fairness in dialectical discussion.