Seleucus (or
Seleukos)
of Seleucia (born
c. 190 BC,
fl.Floruit is a verb meaning 'flourished', which denotes the period of time during which a person, school, movement or even species was active or flourishing...
150s BC) was a
HellenisticHellenistic civilization represents the zenith of Greek influence in the ancient world from 323 BC to about 146 BC ; note, however that Koine Greek language and Hellenistic philosophy and religion are also indisputably elements of the Roman era till Late Antiquity...
astronomer and philosopher from the
SeleuciaSeleucia was the first capital of the Seleucid Empire, and one of the great cities of antiquity standing in Mesopotamia, on the Tigris River.Seleucia may refer to:...
region of
MesopotamiaMesopotamia "land between the rivers" is a name for the Tigris–Euphrates region in the eastern Mediterranean, largely corresponding to Iraq, as well as northeastern Syria, some parts of southeastern Turkey, and some parts of the Khūzestān Province of southwestern...
who supported the
heliocentric theoryIn astronomy, heliocentrism is the theory that the Sun is stationary and at the center of the universe. The word came from the Greek . Historically, heliocentrism was opposed to geocentrism, which placed the Earth at the center. Discussions on the possibility of heliocentrism date to classical...
of planetary motion. Seleucus is known from the writings of
PlutarchPlutarch, born Plutarchos then, on his becoming a Roman citizen, Lucius Mestrius Plutarchus , c. AD 46 – 120, was a Greek historian, biographer, essayist, and Middle Platonist known primarily for his Parallel Lives and Moralia...
,
StraboStrabo was a Greek historian, geographer and philosopher.-Life:Strabo was born in a wealthy family from Amaseia in Pontus , which had recently become part of the Roman Empire.. He studied under various geographers and philosophers; first in Nysa, later in Rome...
and
AetiusAetius was a 1st or 2nd century BCE peripatetic philosopher.None of Aetius' works survive today, but he solves a mystery about two major compilations of philosophical quotes. There are two extant books named Placita Philosophorum and Eclogae Physicae. The first of these is Pseudo-Plutarch and the...
. He was a
ChaldeaChaldea or Chaldaea , "the Chaldeans" of the KJV Old Testament, was a Hellenistic designation for a part of Babylonia, which became an independent kingdom under the Chaldees...
n born in
Seleucia on the TigrisSeleucia 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 Opis .-Seleucid empire:...
in
BabyloniaBabylonia was a civilization in Lower Mesopotamia , with Babylon as its capital. Babylonia emerged when Hammurabi created an empire out of the territories of the former kingdoms of Sumer and Akkad...
.
Teaching around 150 BC, he is known to have been the only follower of the
heliocentric theoryIn astronomy, heliocentrism is the theory that the Sun is stationary and at the center of the universe. The word came from the Greek . Historically, heliocentrism was opposed to geocentrism, which placed the Earth at the center. Discussions on the possibility of heliocentrism date to classical...
of
Aristarchus of SamosAristarchus was a Greek astronomer and mathematician, born on the island of Samos, in Greece. He was the first person to present an explicit argument for a 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
SunThe Sun is the star at the center of the Solar System. The Earth and other matter orbit the Sun, which by itself accounts for about 99.86% of the Solar System's mass....
.
Seleucus (or
Seleukos)
of Seleucia (born
c. 190 BC,
fl.Floruit is a verb meaning 'flourished', which denotes the period of time during which a person, school, movement or even species was active or flourishing...
150s BC) was a
HellenisticHellenistic civilization represents the zenith of Greek influence in the ancient world from 323 BC to about 146 BC ; note, however that Koine Greek language and Hellenistic philosophy and religion are also indisputably elements of the Roman era till Late Antiquity...
astronomer and philosopher from the
SeleuciaSeleucia was the first capital of the Seleucid Empire, and one of the great cities of antiquity standing in Mesopotamia, on the Tigris River.Seleucia may refer to:...
region of
MesopotamiaMesopotamia "land between the rivers" is a name for the Tigris–Euphrates region in the eastern Mediterranean, largely corresponding to Iraq, as well as northeastern Syria, some parts of southeastern Turkey, and some parts of the Khūzestān Province of southwestern...
who supported the
heliocentric theoryIn astronomy, heliocentrism is the theory that the Sun is stationary and at the center of the universe. The word came from the Greek . Historically, heliocentrism was opposed to geocentrism, which placed the Earth at the center. Discussions on the possibility of heliocentrism date to classical...
of planetary motion. Seleucus is known from the writings of
PlutarchPlutarch, born Plutarchos then, on his becoming a Roman citizen, Lucius Mestrius Plutarchus , c. AD 46 – 120, was a Greek historian, biographer, essayist, and Middle Platonist known primarily for his Parallel Lives and Moralia...
,
StraboStrabo was a Greek historian, geographer and philosopher.-Life:Strabo was born in a wealthy family from Amaseia in Pontus , which had recently become part of the Roman Empire.. He studied under various geographers and philosophers; first in Nysa, later in Rome...
and
AetiusAetius was a 1st or 2nd century BCE peripatetic philosopher.None of Aetius' works survive today, but he solves a mystery about two major compilations of philosophical quotes. There are two extant books named Placita Philosophorum and Eclogae Physicae. The first of these is Pseudo-Plutarch and the...
. He was a
ChaldeaChaldea or Chaldaea , "the Chaldeans" of the KJV Old Testament, was a Hellenistic designation for a part of Babylonia, which became an independent kingdom under the Chaldees...
n born in
Seleucia on the TigrisSeleucia 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 Opis .-Seleucid empire:...
in
BabyloniaBabylonia was a civilization in Lower Mesopotamia , with Babylon as its capital. Babylonia emerged when Hammurabi created an empire out of the territories of the former kingdoms of Sumer and Akkad...
.
Teaching around 150 BC, he is known to have been the only follower of the
heliocentric theoryIn astronomy, heliocentrism is the theory that the Sun is stationary and at the center of the universe. The word came from the Greek . Historically, heliocentrism was opposed to geocentrism, which placed the Earth at the center. Discussions on the possibility of heliocentrism date to classical...
of
Aristarchus of SamosAristarchus was a Greek astronomer and mathematician, born on the island of Samos, in Greece. He was the first person to present an explicit argument for a 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
SunThe Sun is the star at the center of the Solar System. The Earth and other matter orbit the Sun, which by itself accounts for about 99.86% of the Solar System's mass....
. According to
PlutarchPlutarch, born Plutarchos then, on his becoming a Roman citizen, Lucius Mestrius Plutarchus , c. AD 46 – 120, was a Greek historian, biographer, essayist, and Middle Platonist known primarily for his Parallel Lives and Moralia...
, Seleucus was the first to prove the heliocentric system through
reasoningReasoning is the cognitive process of looking for reasons for beliefs, conclusions, actions or feelings.Humans have the ability to engage in reasoning about their own reasoning. Different forms of such reflection on reasoning occur in different fields...
, but it is not known what arguments he used.
Tides
According to
Lucio RussoLucio Russo is an Italian physicist, mathematician and historian of science. Born in Venice, he teaches at the University of Rome Tor Vergata....
, Seleucus' arguments for a heliocentric theory were probably related to the phenomenon of
tideTides are the rises and falls of sea level caused by the combined effect of rotation of the Earth and the gravitation of the Moon and the Sun. The tides occur with a period of approximately 12 and a half hours and are influenced by the shape of the near-shore bottom.Most coastal areas experience...
s. Seleucus correctly theorized that
tideTides are the rises and falls of sea level caused by the combined effect of rotation of the Earth and the gravitation of the Moon and the Sun. The tides occur with a period of approximately 12 and a half hours and are influenced by the shape of the near-shore bottom.Most coastal areas experience...
s were caused by the
MoonThe Moon is Earth's only natural satellite and the fifth largest satellite in the Solar System. The average centre-to-centre distance from the Earth to the Moon is , about thirty times the diameter of the Earth. The common centre of mass of the system is located at about —a quarter the Earth's...
, although he believed that the interaction was mediated by the
pneumaPneuma is an ancient Greek word for "breath," and in a religious context for "spirit" or "soul." It is given various technical meanings by medical writers and philosophers of antiquity, including:...
. He noted that the tides varied in time and strength in different parts of the world.
According to
StraboStrabo was a Greek historian, geographer and philosopher.-Life:Strabo was born in a wealthy family from Amaseia in Pontus , which had recently become part of the Roman Empire.. He studied under various geographers and philosophers; first in Nysa, later in Rome...
(1.1.9), Seleucus was the first to state that the
tideTides are the rises and falls of sea level caused by the combined effect of rotation of the Earth and the gravitation of the Moon and the Sun. The tides occur with a period of approximately 12 and a half hours and are influenced by the shape of the near-shore bottom.Most coastal areas experience...
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.
Computational model
According to
Bartel Leendert van der WaerdenBartel Leendert van der Waerden was a Dutch mathematician.Van der Waerden learned advanced mathematics at the University of Amsterdam and the University of Göttingen, from 1919 until 1926.He was much influenced by Emmy Noether at Göttingen. Amsterdam awarded him a Ph.D...
, Seleucus may have proved the heliocentric theory by determining the constants of a
geometricGeometry 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 for the heliocentric theory and by developing methods to compute planetary positions using this model, as
Nicolaus CopernicusNicolaus Copernicus was the first astronomer 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
trigonometricTrigonometry is a branch of mathematics that deals with triangles, particularly those plane triangles in which one angle has 90 degrees...
methods that were available in his time, as he was a contemporary of
HipparchusHipparchus, 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 of Pontus or
Heraclides PonticusHeraclides Ponticus , also known as Herakleides, was a Greek philosopher who lived and died at Heraclea Pontica, now Karadeniz Ereğli, Turkey....
(387 BC-312 BC), the
inferiorThe terms "inferior planet" and "superior planet" were originally used in the geocentric cosmology of Claudius Ptolemy to differentiate those planets having an epicycle that remained collinear with the Earth and Sun, compared to the planets that did not.In the 16th century, the terms were...
planets
MercuryFor the liquid metallic element, see Mercury .Mercury is the innermost and smallest planet in the Solar System, orbiting the Sun once every 87.969 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...
and
VenusVenus is the second-closest planet to 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...
are named at times solar planets, as they do not leave the Sun for more than a certain angle.