Seleucus of Seleucia
Encyclopedia
Seleucus of Seleucia (born c. 190 BC, fl.
150s BC) was a Hellenistic astronomer and philosopher. Coming from Seleucia on the Tigris
, the capital of the Seleucid empire
, or, alternatively, Seleukia on the Red Sea
, he is best known as a proponent of heliocentrism
and for his theory of the origin of tide
s.
, which stated that the Earth rotated around its own axis which in turn revolved around the Sun
. According to Plutarch, Seleucus was the first to demonstrate the heliocentric system through reasoning, but it is not known what arguments he used. According to Bartel Leendert van der Waerden
, Seleucus may have constructed his heliocentric theory by determining the constants of a geometric
model and by developing methods to compute planetary positions using this model, as Nicolaus Copernicus
later did in the 16th century. He may have used trigonometric
methods that were available in his time, as he was a contemporary of Hipparchus
.
Since the time of Heraclides Ponticus
(387 BC–312 BC), the inferior
planets Mercury
and Venus
are named at times solar planets, as their positions diverge from the Sun by only a small angle.
According to the Greek geographer Strabo
, Seleucus was also the first to assume the universe to be infinite. None of his original writings or Greek translations have survived, though a fragment of his work has survived only in Arabic
translation, which was later referred to by the Persian philosopher
Muhammad ibn Zakariya al-Razi (865–925).
, Seleucus' arguments for a heliocentric theory were probably related to the phenomenon of tide
s. Seleucus correctly theorized that tide
s were caused by the Moon
, although he believed that the interaction was mediated by the pneuma
. He noted that the tides varied in time and strength in different parts of the world. According to Lucio Russo
, Seleucus ascribed tide
s both to the Moon
and to a whirling motion of the Earth
, which could be interpreted as the motion of the Earth
around the Earth
-Moon
center of mass
.
According to Strabo
(1.1.9), Seleucus was the first to state that the tide
s are due to the attraction of the Moon, and that the height of the tides depends on the Moon's position relative to the Sun.
, Aetius
, and Strabo
, all of whom were Greeks, and the Persian Muhammad ibn Zakariya al-Razi. Strabo lists Seleucus as one of the four most influential "Chaldea
n" astronomers:
Floruit
Floruit , abbreviated fl. , is a Latin verb meaning "flourished", denoting the period of time during which something was active...
150s BC) was a Hellenistic astronomer and philosopher. Coming from Seleucia on the Tigris
Seleucia on the Tigris
Seleucia , also known as Seleucia on the Tigris, was one of the great cities of the world during Hellenistic and Roman times. It stood in Mesopotamia, on the west bank of the Tigris River, opposite the smaller town of Ctesiphon, in present day Babil Governorate, Iraq.-Seleucid empire:Seleucia,...
, the capital of the Seleucid empire
Seleucid Empire
The Seleucid Empire was a Greek-Macedonian state that was created out of the eastern conquests of Alexander the Great. At the height of its power, it included central Anatolia, the Levant, Mesopotamia, Persia, today's Turkmenistan, Pamir and parts of Pakistan.The Seleucid Empire was a major centre...
, or, alternatively, Seleukia on the Red Sea
Erythraean Sea
The Erythraean Sea is one of the names found in ancient cartography. This name may have derived from the seasonal blooms of the red-coloured Trichodesmium erythraeum near the water's surface, as the Greek "Ερυθρά" actually means "red".In the third century, Flavius Philostratus made this comment:...
, he is best known as a proponent of heliocentrism
Heliocentrism
Heliocentrism, or heliocentricism, is the astronomical model in which the Earth and planets revolve around a stationary Sun at the center of the universe. The word comes from the Greek . Historically, heliocentrism was opposed to geocentrism, which placed the Earth at the center...
and for his theory of the origin of tide
Tide
Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the moon and the sun and the rotation of the Earth....
s.
Heliocentric theory
Teaching around 150 BC, he is known to have been a follower of the heliocentric theory of Aristarchus of SamosAristarchus of Samos
Aristarchus, or more correctly Aristarchos , was a Greek astronomer and mathematician, born on the island of Samos, in Greece. He presented the first known heliocentric model of the solar system, placing the Sun, not the Earth, at the center of the known universe...
, which stated that the Earth rotated around its own axis which in turn revolved around the Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
. According to Plutarch, Seleucus was the first to demonstrate the heliocentric system through reasoning, but it is not known what arguments he used. According to Bartel Leendert van der Waerden
Bartel Leendert van der Waerden
Bartel Leendert van der Waerden was a Dutch mathematician and historian of mathematics....
, Seleucus may have constructed his heliocentric theory by determining the constants of a geometric
Geometry
Geometry arose as the field of knowledge dealing with spatial relationships. Geometry was one of the two fields of pre-modern mathematics, the other being the study of numbers ....
model and by developing methods to compute planetary positions using this model, as Nicolaus Copernicus
Nicolaus Copernicus
Nicolaus Copernicus was a Renaissance astronomer and the first person to formulate a comprehensive heliocentric cosmology which displaced the Earth from the center of the universe....
later did in the 16th century. He may have used trigonometric
Trigonometry
Trigonometry is a branch of mathematics that studies triangles and the relationships between their sides and the angles between these sides. Trigonometry defines the trigonometric functions, which describe those relationships and have applicability to cyclical phenomena, such as waves...
methods that were available in his time, as he was a contemporary of Hipparchus
Hipparchus
Hipparchus, the common Latinization of the Greek Hipparkhos, can mean:* Hipparchus, the ancient Greek astronomer** Hipparchic cycle, an astronomical cycle he created** Hipparchus , a lunar crater named in his honour...
.
Since the time of Heraclides Ponticus
Heraclides Ponticus
Heraclides Ponticus , also known as Herakleides and Heraklides of Pontus, was a Greek philosopher and astronomer who lived and died at Heraclea Pontica, now Karadeniz Ereğli, Turkey. He is best remembered for proposing that the earth rotates on its axis, from west to east, once every 24 hours...
(387 BC–312 BC), the inferior
Inferior and superior planets
The terms "inferior planet" and "superior planet" were originally used in the geocentric cosmology of Claudius Ptolemy to differentiate as 'inferior' those planets whose epicycle remained collinear with the Earth and Sun, compared to the 'superior' planets that did not.In the 16th century, the...
planets Mercury
Mercury (planet)
Mercury is the innermost and smallest planet in the Solar System, orbiting the Sun once every 87.969 Earth days. The orbit of Mercury has the highest eccentricity of all the Solar System planets, and it has the smallest axial tilt. It completes three rotations about its axis for every two orbits...
and Venus
Venus
Venus is the second planet from the Sun, orbiting it every 224.7 Earth days. The planet is named after Venus, the Roman goddess of love and beauty. After the Moon, it is the brightest natural object in the night sky, reaching an apparent magnitude of −4.6, bright enough to cast shadows...
are named at times solar planets, as their positions diverge from the Sun by only a small angle.
According to the Greek geographer Strabo
Strabo
Strabo, also written Strabon was a Greek historian, geographer and philosopher.-Life:Strabo was born to an affluent family from Amaseia in Pontus , a city which he said was situated the approximate equivalent of 75 km from the Black Sea...
, Seleucus was also the first to assume the universe to be infinite. None of his original writings or Greek translations have survived, though a fragment of his work has survived only in Arabic
Arabic language
Arabic is a name applied to the descendants of the Classical Arabic language of the 6th century AD, used most prominently in the Quran, the Islamic Holy Book...
translation, which was later referred to by the Persian philosopher
Iranian philosophy
Iranian philosophy or Persian philosophy can be traced back as far as to Old Iranian philosophical traditions and thoughts which originated in ancient Indo-Iranian roots and were considerably influenced by Zarathustra's teachings...
Muhammad ibn Zakariya al-Razi (865–925).
Tides
According to Lucio RussoLucio Russo
Lucio Russo is an Italian physicist, mathematician and historian of science. Born in Venice, he teaches at the Mathematics Department of the Science College in the University of Rome Tor Vergata....
, Seleucus' arguments for a heliocentric theory were probably related to the phenomenon of tide
Tide
Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the moon and the sun and the rotation of the Earth....
s. Seleucus correctly theorized that tide
Tide
Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the moon and the sun and the rotation of the Earth....
s were caused by the Moon
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...
, although he believed that the interaction was mediated by the pneuma
Pneuma
Pneuma is an ancient Greek word for "breath," and in a religious context for "spirit" or "soul." It has various technical meanings for medical writers and philosophers of classical antiquity, particularly in regard to physiology, and is also used in Greek translations of the Hebrew Bible and in...
. He noted that the tides varied in time and strength in different parts of the world. According to Lucio Russo
Lucio Russo
Lucio Russo is an Italian physicist, mathematician and historian of science. Born in Venice, he teaches at the Mathematics Department of the Science College in the University of Rome Tor Vergata....
, Seleucus ascribed tide
Tide
Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the moon and the sun and the rotation of the Earth....
s both to the Moon
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...
and to a whirling motion of the Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
, which could be interpreted as the motion of the Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
around the Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
-Moon
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...
center of mass
Center of mass
In physics, the center of mass or barycenter of a system is the average location of all of its mass. In the case of a rigid body, the position of the center of mass is fixed in relation to the body...
.
According to Strabo
Strabo
Strabo, also written Strabon was a Greek historian, geographer and philosopher.-Life:Strabo was born to an affluent family from Amaseia in Pontus , a city which he said was situated the approximate equivalent of 75 km from the Black Sea...
(1.1.9), Seleucus was the first to state that the tide
Tide
Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the moon and the sun and the rotation of the Earth....
s are due to the attraction of the Moon, and that the height of the tides depends on the Moon's position relative to the Sun.
Seleucus in Strabo
Seleucus is known from the writings of PlutarchPlutarch
Plutarch then named, on his becoming a Roman citizen, Lucius Mestrius Plutarchus , c. 46 – 120 AD, was a Greek historian, biographer, essayist, and Middle Platonist known primarily for his Parallel Lives and Moralia...
, Aetius
Aetius (philosopher)
Aetius was a 1st or 2nd century doxographer and Eclectic philosopher.None of Aetius' works survive today, but he solves a mystery about two major compilations of philosophical quotes...
, and Strabo
Strabo
Strabo, also written Strabon was a Greek historian, geographer and philosopher.-Life:Strabo was born to an affluent family from Amaseia in Pontus , a city which he said was situated the approximate equivalent of 75 km from the Black Sea...
, all of whom were Greeks, and the Persian Muhammad ibn Zakariya al-Razi. Strabo lists Seleucus as one of the four most influential "Chaldea
Chaldea
Chaldea or Chaldaea , from Greek , Chaldaia; Akkadian ; Hebrew כשדים, Kaśdim; Aramaic: ܟܐܠܕܘ, Kaldo) was a marshy land located in modern-day southern Iraq which came to briefly rule Babylon...
n" astronomers:
In Chapter XVI of his GeographiaGéographicaGéographica is the French-language magazine of the Royal Canadian Geographical Society , published under the Society's French name, the Société géographique royale du Canada . Introduced in 1997, Géographica is not a stand-alone publication, but is published as an irregular supplement to La...
, Strabo mentions several "Chaldaen" astronomers. At the end he adds: "Seleukios of Seleukia was a Chaldaean too." ... Babylonian astrologers and astronomers were often called "Chaldaeans." Strabo calls them "the so-called Chaldaeans". Their writings were translated into Greek and used by later authors like Geminos. The "Chaldaean" astronomers mentioned by Strabo are Kidenas, NaburianosNaburimannuNabu-ri-man-nu was a Chaldean astronomer and mathematician.Classical and ancient cuneiform sources mention an astronomer with this name:...
, Sudines, and Seleukos. The first two are also known from astronomical cuneiform texts under their Akkadian names Nabu-Rimannu and Kidinnu.
See also
- Babylonian astronomy
- Greek astronomyGreek astronomyGreek astronomy is astronomy written in the Greek language in classical antiquity. Greek astronomy is understood to include the ancient Greek, Hellenistic, Greco-Roman, and Late Antiquity eras. It is not limited geographically to Greece or to ethnic Greeks, as the Greek language had become the...