Seleucus of Seleucia ( el, Σέλευκος ''Seleukos''; born c. 190 BC;
fl. c. 150 BC) was a
Hellenistic astronomer and philosopher. Coming from
Seleucia on the Tigris
Seleucia (; grc-gre, Σελεύκεια), also known as or , was a major Mesopotamian city of the Seleucid empire. It stood on the west bank of the Tigris River, within the present-day Baghdad Governorate in Iraq.
Name
Seleucia ( grc-gre, Σ ...
,
Mesopotamia
Mesopotamia ''Mesopotamíā''; ar, بِلَاد ٱلرَّافِدَيْن or ; syc, ܐܪܡ ܢܗܪ̈ܝܢ, or , ) is a historical region of Western Asia situated within the Tigris–Euphrates river system, in the northern part of the ...
, the capital of the
Seleucid Empire, or, alternatively, Seleukia on the
Erythraean Sea
The Erythraean Sea ( grc-gre, Ἐρυθρὰ Θάλασσα, ''Erythrà Thálassa'', ."Red Sea") was a former maritime designation that always included the Gulf of Aden and at times other seas between Arabia Felix and the Horn of Africa. Origin ...
, he is best known as a proponent of
heliocentrism and for his theory of the origin of
tide
Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon (and to a much lesser extent, the Sun) and are also caused by the Earth and Moon orbiting one another.
Tide tables ...
s.
Heliocentric theory
Seleucus is known to have supported the heliocentric theory of
Aristarchus of Samos, which stated that the
Earth rotated around its own axis which in turn revolved around the
Sun
The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...
. According to
Plutarch
Plutarch (; grc-gre, Πλούταρχος, ''Ploútarchos''; ; – after AD 119) was a Greek Middle Platonist philosopher, historian, biographer, essayist, and priest at the Temple of Apollo in Delphi. He is known primarily for hi ...
, 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 (; 2 February 1903 – 12 January 1996) was a Dutch mathematician and historian of mathematics.
Biography
Education and early career
Van der Waerden learned advanced mathematics at the University of Amster ...
, 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
Nicolaus Copernicus (; pl, Mikołaj Kopernik; gml, Niklas Koppernigk, german: Nikolaus Kopernikus; 19 February 1473 – 24 May 1543) was a Renaissance polymath, active as a mathematician, astronomer, and Catholic canon, who formulated ...
later did in the 16th century. He may have used
trigonometric
Trigonometry () is a branch of mathematics that studies relationships between side lengths and angles of triangles. The field emerged in the Hellenistic world during the 3rd century BC from applications of geometry to astronomical studies. ...
methods that were available in his time, as he was a contemporary of
Hipparchus
Hipparchus (; el, Ἵππαρχος, ''Hipparkhos''; BC) was a Greek astronomer, geographer, and mathematician. He is considered the founder of trigonometry, but is most famous for his incidental discovery of the precession of the equi ...
.
Since the time of
Heraclides Ponticus (387 BC–312 BC), the
inferior planets
Mercury and
Venus
Venus is the second planet from the Sun. It is sometimes called Earth's "sister" or "twin" planet as it is almost as large and has a similar composition. As an interior planet to Earth, Venus (like Mercury) appears in Earth's sky never f ...
have been at times named ''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 have survived, though a fragment of his work has survived only in
Arabic
Arabic (, ' ; , ' or ) is a Semitic language spoken primarily across the Arab world.Semitic languages: an international handbook / edited by Stefan Weninger; in collaboration with Geoffrey Khan, Michael P. Streck, Janet C. E.Watson; Walter ...
translation, which was later referred to by the
Persian philosopher Muhammad ibn Zakariya al-Razi (865–925).
Tides
According to
Lucio Russo, Seleucus' arguments for a heliocentric theory were probably related to the phenomenon of
tide
Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon (and to a much lesser extent, the Sun) and are also caused by the Earth and Moon orbiting one another.
Tide tables ...
s.
[ Lucio Russo, ''Flussi e riflussi'', Feltrinelli, Milano, 2003, .] The annual cycle of tides (which was studied by Seleucus) can indeed hardly be explained in a geocentric system. Seleucus correctly theorized that
tide
Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon (and to a much lesser extent, the Sun) and are also caused by the Earth and Moon orbiting one another.
Tide tables ...
s were caused by 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 ...
, explaining that the interaction was mediated by the
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 ...
. He noted that the tides varied in time and strength in different parts of the world. According to
Lucio Russo, Seleucus ascribed
tide
Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon (and to a much lesser extent, the Sun) and are also caused by the Earth and Moon orbiting one another.
Tide tables ...
s both to 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 ...
and to a whirling motion of the
Earth
Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...
, which could be interpreted as the motion of the
Earth
Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...
around the
Earth
Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...
-
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 ...
center of mass.
According to
Strabo (1.1.9), Seleucus was the first to state that the
tide
Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon (and to a much lesser extent, the Sun) and are also caused by the Earth and Moon orbiting one another.
Tide tables ...
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
Plutarch
Plutarch (; grc-gre, Πλούταρχος, ''Ploútarchos''; ; – after AD 119) was a Greek Middle Platonist philosopher, historian, biographer, essayist, and priest at the Temple of Apollo in Delphi. He is known primarily for hi ...
,
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 "
Chaldean" astronomers:
In Chapter XVI of his Geographia
The ''Geography'' ( grc-gre, Γεωγραφικὴ Ὑφήγησις, ''Geōgraphikḕ Hyphḗgēsis'', "Geographical Guidance"), also known by its Latin names as the ' and the ', is a gazetteer, an atlas, and a treatise on cartography, com ...
, 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, Naburianos, 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
Babylonian astronomy was the study or recording of celestial objects during the early history of Mesopotamia.
Babylonian astronomy seemed to have focused on a select group of stars and constellations known as Ziqpu stars. These constellations ...
*
Greek astronomy
Greek 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 e ...
*
Discourse on the Tides
References
Sources
*
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*
{{Authority control
190s BC births
150s BC deaths
2nd-century BC scholars
Babylonian astronomers
People of the Seleucid Empire
Chaldea