Greece

Astronomy
in ancient Greece

Greek myths and legends around stars, planets and constellations date back to the seventh century BC and the epic poems attributed to Homer and Hesiod.

Today, Most of the common names of the stars, planets, and constellations of the northern hemisphere are inherited from Greek mythology.

The primary focus of this site is not astronomy, but Star Lore, which is folklore based upon stars and star patterns. We try to create a collection of mythical stories about stars and constellations from all over the world. However, to better understand and interpret the stories, a brief history of the astronomy of different cultures might be helpful.

This is by no means a scientific paper on the history of Greek astronomy, but merely an illustrated collection of highlights of that history, along with some links to what we think are reliable sources on the subject.

Ian Ridpath and Wikipedia both provide excellent summaries of ancient Greek astronomy.

This portion of our site is about the history of ancient Greek astronomy.

Click here to discover the world of Greek Star Lore.

Bits of History of Greek Astronomy

Early Greek Lyrics
The Odyssey, which is believed to have been written in the early seventh century BC mentions the constellations Orion, Boötes and Ursa Major, the star clusters of the Pleiades and Hyades and the brightest star in the night sky, Sirius.

While there are no written record, it is believed that Greek philosophers and scientists were aware of the five visible planets at least since the fifth century BC. The word "planet" has its roots in the Greek term πλανήτης (planētēs), which means "wanderer."
Odysseus and the Sirens, ca. 480-470 BC
Source: Wikipedia

Thales of Miletus (c. 624 – c. 546 BC)
Thales of Miletus was was a philosopher, mathematician amd astronomer. He attempted to explain natural phenomena without reference to mythology and was tremendously influential in this respect. Thales' rejection of mythological explanations became an essential idea for the scientific revolution.

Thales described the position of Ursa Minor and suggested that the constellation might be useful as a guide for navigation at sea.

Thales is reported to have predicted a solar eclipse on May 28, 585 BC.

Sources: Wikipedia, Science Source
Thales of Miletus
by Jacob de Gheyn III
Source: Rijksmuseum Amsterdam

Anaximander (c. 610 – c. 546 BC)
Anaximander was a student of Thales and is believed to be a teacher of Pythagoras. Inspired by his teacher, he was the first to exercise a scientific, non-mythological approach to explain the movements of celestial bodies.

Anaximander is credited with oldest prose document about the Universe; for this he is often called the "Father of Cosmology." He was the first to conceive a mechanical model of the world. His revolutionary concept of the Earth floating free in space without falling is considered by many as the first cosmological revolution and the starting point of scientific thinking.

Sources: Wikipedia, Internet Encyclopedia of Philosophy, famousscientists.org
Couprie, Kočandrle: Anaximander’s‘Boundless Nature’

Anaximander, holding a sundial
Source: Wikipedia

The Pythagoreans
ThePythagoreans were followers of the teachings and beliefs held by Pythagoras (c. 570 – c. 495 BC). Their teachings had a profound influence on Plato and Aristotle and thus on all of Western philosophy and science.

The Pythagoreans considered astronomy a part of the Quadrivium, the four mathematical arts (along with arithmetic, geometry, and music). The Pythagorean Philolaus ( c. 470 – c. 385 BC) developed a first coherent system in which celestial bodies move in circles. He was also the first to move the Earth out of the center of the universe, making it just one of the planets. In Pythagorean astronomy, ten celestial entities, the Earth, a fictional "Counter-Earth" (Antichthon), the Sun, the Moon, the five known planets and the stars circled a Central Fire.

Source: Wikipedia
Pythagoras in Raphael's fresco The School of Athens
Source: Wikipedia

Anaxagoras (c. 500 BC – c. 428 BC)
Philosopher Anaxagoras was the first to describe stars as fiery stones like our sun, just further away. He also suggested that the Milky Way may be a concentration of distant stars.

Anaxagoras described the Sun as a "mass of blazing metal, larger than the Peloponnese." His description of the Sun as a physical entity and his denial of the existence of a solar or lunar deity had him face a trial similar to that of Galileo Galilei 2000 years later. In 450 BC, he was exiled from Athens.

Source: Wikipedia
Anaxagoras by Carl Rahl; ca. 1888
Source: Wikipedia

The Platonic Academy (387 BC)
Athenian philosopher Plato (ca.428 - ca. 348 BC) is widely considered the pivotal figure in the history of Ancient Greek and Western philosophy, along with his teacher, Socrates, and his most famous student, Aristotle.

In 387 BC), Plato founded the Academy, the first institution of higher learning in the Western world.

The Academy promotes the idea that everything in the universe moves in harmony and that the Sun, Moon, and planets move around Earth in perfect circles.

Source: Wikipedia

Plato’s Academy; Mosaic in Pompeii
Source: Wikipedia

Eudoxus (c. 390 BC – c. 337 BC)
Encouraged by Plato, mathematician Eudoxus of Cnidus introduced geometry into the calculation of the movement of celestial bodies.

His geocentric model divided the cosmos into two regions, a central and motionless spherical Earth and a spherical heavenly realm centered on the Earth.

Eudoxus also developed a first comprehensive star catalogue, containing a full set of the classical constellations. While his original writing, called Phaenomena is lost, his catalogue was rewritten between 275 and 250 BC by Aratus of Soli.

Eudoxus' concepts are widely considered the base of Greek astronomy.

Source: Wikipedia

Two Sphere Model
Source: Wikipedia

During Eudoxus' lifetime, knowledge of the Babylonian MUL.APIN star catalogue had spread through the ancient world and Eudoxus reputedly learned about the Mesopotamian constellations from priests in Egypt and introduced them to Greece.

Aratus’s rewriting of Phaenomena provides a complete list of the constellations known in ancient Greece. The names of some of the brightest stars in the northern Sky, among them Sirius, Procyon and Arcturus, can also be traced back to Aratus.

In spite of this extensive work on constellations, Eudoxus' geocentric model caused Greek astronomy to shift from stellar to planetary concerns. Back then, the planets, now known by their Roman names, were named after Greek Gods: Hermes (Mercury), Aphrodite (Venus), Ares (Mars), Zeus (Jupiter), and Cronus (Saturn).

Source: Wikipedia and Ian Ridpath

Aristotle (384 – 322 BC)
Famous Greek philosopher Aristotle was the leading authorities of his time in many fields of science such as physics, biology and geology. He is usually not listed among the great Greek astronomers but one of his observations deserves mentioning.

In 325 BC, Aristotle writes in Book I of the Meteorologica, that "... a star below Sirius was seen to have a faint tail" and that "... if you looked hard at it the light used to become dim, but to less intent glance it was brighter".

In the 19th century, Irish astronomer John Ellard Gore theorized that the "star" observed by Aristotle might have been the star cluster M41 (or NGC 2287), which would make Aristotle's observation the first record of a star cluster.

Sources: messier.seds.org, Wikipedia

Aristaotle
Source: Wikipedia

Aristarchus (c. 310 BC – c. 230 BC)
From the time of Eudoxus until well into the Middle Ages, the geocentric model was the commonly accepted concept of cosmology. But the idea of a heliocentric world, most commonly attributed to Copernicus, was first conceived in ancient Greece.

When Aristarchus of Samos calculated the relative sizes of the Earth, the Moon and the Sun, he deducted that the largest object (the Sun) would have the most attractive force and therefor should be the center. Thus, Aristarchus developed a first concept of gravity long before Newton.

Aristarchus also suspected the stars were other, far away suns. During his life time and for the next seven centuries, his revolutionary ideas were mostly dismissed and at best discussed as a mere speculations.

Source: Wikipedia
Aristarchus of Samos
Source: Wikipedia

Aratus (c. 310 – c. 240 BC)
Aratus of Soli was a Greek poet. His only surviving work is the Phaenomena, a verse setting of a lost work of the same name by Eudoxus of Cnidus.

Aratus' poem describes the constellations and other celestial phenomena. although his descriptions contain a number of errors and inconsistencies, his poem was very popular in the Greek and Roman world. There have been several Latin translations, which in turn were the base for other translation. The Theoi Classical Texts Library provides an English translation of the Phaenomena.

Source: Wikipedia

Aratus with an astronomical sphere
Source: Wikipedia

Eratosthenes (c. 276 – c. 195 BC)
Mathematician, geographer, poet and astronomer Eratosthenes was told that on midsummer day (June 21) in the town of Syene in southern Egypt (today Aswan) the noontime Sun was reflected in a deep well, meaning that it was right overhead, at zenith. On midsummer day in 240 BC, Eratosthenes measured the height of the sun in Alexandria (578 miles north of Syene) and detected a difference of 1/50 of the circle, that is, 7. 2 degrees, and from that he estimated the circumference of the Earth to be 250,000 stadia or 39,375 km, which is 1.4% less than the real number, 40,076 km.

Sources: Wikipedia, phy6.or

19th-century reconstruction of Eratosthenes'
map of the known world, ca. 194 BC
Source: Wikipedia

Hipparchus (c. 190 – c. 120 BC)
Hipparchus of Nicaea is considered the founder of trigonometry. His greatest achievements in the field of astronomy are the discovery of the precession of the equinoxes and a star catalogue containing the positions of at least 850 stars. Based on his observations, he constructed a celestial globe depicting the constellations. When Hipparchus compared his observations with earlier star charts, he discovered that the longitude of the stars had changed over time, which led him to determine the first value of the precession of the equinoxes.

Hipparchus's star catalogue has gotten lost, but in the first century BC it was used by Ptolemy, who extended it to 1,022 stars.

Source: Wikipedia

Hipparchus and his celestial globe
Fresco: The School of Athens
Source: Wikipedia

Antikythera mechanism (ca. between 200 BC and 100 BC)
The Antikythera mechanism is the oldest known example of a hand-powered analogue computer. It could have been used to predict astronomical positions and eclipses for calendar and astrological purposes decades in advance.

The artifact was retrieved in 1901 from a shipwreck off the coast of the Greek island Antikythera.

Source: Wikipedia
Antikythera mechanism (Fragment)
Source: Wikipedia

Germanicus' Phaenomena (4 AD)
In 4 AD, Roman general and poet Germanicus wrote a Latin version of Aratus's Phainomena, slightly rewriting the contents of the original.

For his work, Germanicus is considered one of the leading Roman writers on astronomy.

Source: Wikipedia
Germanicus on a Roman Coin
Source: Wikipedia

Marcus Manilius' Astronomica (ca. 30-40 AD)
Around 30 to 40 AD, Roman poet and astrologer Marcus Manilius wrote a rather lengthy poem on celestial phenomena called Astronomica; written in hexameters and divided into five books.

Astronomica concentrates on the constellations of the Zodiac.

Manilius is sometimes considered the father of Astrology. To his credit, it should be mentioned that at his time there was no clear distinction between the science of astronomy and the concept of astrology and in spite of it being heavily astrological, Astronomica is, nevertheless, the oldest existing record on the lore of the Greek Zodiac constellations.

Source: Wikipedia
1461 manuscript of Astronomica
Source: Wikipedia

Catasterismi (ca. 100 AD)
Quoting alchetron.com: "Catasterismi (Greek Καταστερισμοί, "placings among the stars") is an Alexandrian prose retelling of the mythic origins of stars and constellations, as they were interpreted in Hellenistic culture. The work survived in an epitome assembled at the end of the 1st century CE, based on a lost original with some possible relation to the work of Eratosthenes of Cyrene; thus the author is alluded to as Pseudo-Eratosthenes.

Catasterismi records the mature and definitive development of a long process: the Hellenes' assimilation of a Mesopotamian zodiac, transmitted through Persian interpreters and translated and harmonized with the known terms of Greek mythology.

While the Catasterismi describes constellations, it is more concerned with the mythological narrative attached to each than with the mathematical tradition of astronomy.

Although there is no absolute distinction between astronomy and astrology in antiquity, intellectual circles in Alexandria during the 1st BCE began to distinguish between astrology for making predictions and astronomical observation for scientific conjecture."

Sources: Wikipedia, alchetron.com
Constellations of the Catasterismi
Johann Konrad Schaubach, 1795 Source: atlascoelestis.com

Ptolemy (c. 90 – c. 186 AD)
Compiling the observations of previous Mesopotamian and Greek astronomers, Claudius Ptolemy compiled a comprehensive treatise on astronomy, originally called Mathēmatikē Syntaxis (Μαθηματικὴ Σύνταξις), the Mathematic Treatise. Later called Hē Megalē Syntaxis (Ἡ Μεγάλη Σύνταξις), The Great Treatise, it became the most influential scientific text on astronomy for centuries to come. It cemented the geocentric model of the Universe for the next fourteen centuries and contained a catalogue of 1,022 stars that remained the standard star catalogue in the Western and Arab worlds for over eight centuries.

Ptolemy in the Alexandria Observatory
Source: sciencephoto.com

Later, in his Planetary Hypotheses, Ptolemy went beyond the mathematical model of the Almagest to present a physical realization of the universe as a set of nested spheres. Ptolemy's star catalogue covered the entire sky as it was visible from Alexandria in the second century AD. His list of forty eight constellations laid the foundation to the modern system of constellations.

Using the Greek term megiste (μεγίστη), Ptolemy's star catalogue was translated into Arabic as al-majisṭī (المجسطي), which in turn became the root of the Latin title Almagestum and the popular English title Almagest.

The first translations into Arabic took place in the 9th century. Based on the Arabic version, the Toledo School of Translators delivered the first successful Latin translation in 1175. Later, in the 15th century Regiomontanus delivered a Latin translation from the original Greek.

Greece's main legacy remains the introduction of the scientific method to astronomy and thus a first clear distinction between astronomy and astrology.

Due to Ptolemy's list of constellation, an enormous portion of today's star lore is based on Greek mythology and for most constellations, the first story one finds is usually a Greek one.

Sources: Wikipedia, Ian Ridpath,
Andrea Murschel: The Structure and Function of Ptolemy's Physical Hypotheses of Planetary Motion