Geminus of
Rhodes
Rhodes (; el, Ρόδος , translit=Ródos ) is the largest and the historical capital of the Dodecanese islands of Greece. Administratively, the island forms a separate municipality within the Rhodes regional unit, which is part of the So ...
( el, Γεμῖνος ὁ Ῥόδιος), was a
Greek
Greek may refer to:
Greece
Anything of, from, or related to Greece, a country in Southern Europe:
*Greeks, an ethnic group.
*Greek language, a branch of the Indo-European language family.
**Proto-Greek language, the assumed last common ancestor ...
astronomer
An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, natural satellite, moons, comets and galaxy, g ...
and
mathematician
A mathematician is someone who uses an extensive knowledge of mathematics in their work, typically to solve mathematical problems.
Mathematicians are concerned with numbers, data, quantity, structure, space, models, and change.
History
On ...
, who flourished in the 1st century BC. An
astronomy
Astronomy () is a natural science that studies astronomical object, celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and chronology of the Universe, evolution. Objects of interest ...
work of his, the ''Introduction to the Phenomena'', still survives; it was intended as an introductory astronomy book for students. He also wrote a work on
mathematics
Mathematics is an area of knowledge that includes the topics of numbers, formulas and related structures, shapes and the spaces in which they are contained, and quantities and their changes. These topics are represented in modern mathematics ...
, of which only fragments quoted by later authors survive.
Life
Nothing is known about the life of Geminus. It is not even certain that he was born in Rhodes, but references to mountains on Rhodes in his astronomical works suggests that he worked there. His dates are not known with any certainty either. A passage in his works referring to the ''Annus Vagus'' (Wandering Year) of the
Egyptian calendar
The ancient Egyptian calendar – a civil calendar – was a solar calendar with a 365-day year. The year consisted of three seasons of 120 days each, plus an intercalary month of five epagomenal days treated as outside of the year proper. Eac ...
of 120 years before his own time, has been used to imply a date of c. 70 BC for the time of writing, which would be consistent with the idea that he may have been a pupil of
Posidonius
Posidonius (; grc-gre, wikt:Ποσειδώνιος, Ποσειδώνιος , "of Poseidon") "of Apamea (Syria), Apameia" (ὁ Ἀπαμεύς) or "of Rhodes" (ὁ Ῥόδιος) (), was a Greeks, Greek politician, astronomer, astrologer, geog ...
, but a date as late as 50 AD has also been suggested.
The crater
Geminus
Geminus of Rhodes ( el, Γεμῖνος ὁ Ῥόδιος), was a Greek astronomer and mathematician, who flourished in the 1st century BC. An astronomy work of his, the ''Introduction to the Phenomena'', still survives; it was intended as an int ...
on 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 ...
is named after him.
Astronomy
The only work of Geminus to survive is his ''Introduction to the Phenomena'' ( el, Εἰσαγωγὴ εἰς τὰ Φαινόμενα), often just called the ''Isagoge''. This introductory astronomy book, based on the works of earlier astronomers such as
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 ...
, was intended to teach astronomy for beginning students in the subject. In it, Geminus describes the
zodiac
The zodiac is a belt-shaped region of the sky that extends approximately 8° north or south (as measured in celestial latitude) of the ecliptic, the Sun path, apparent path of the Sun across the celestial sphere over the course of the year. ...
and the motion of 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 ...
, the
constellation
A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object.
The origins of the e ...
s, the
celestial sphere
In astronomy and navigation, the celestial sphere is an abstract sphere that has an arbitrarily large radius and is concentric to Earth. All objects in the sky can be conceived as being projected upon the inner surface of the celestial sphere, ...
, days and nights, the risings and settings of the zodiacal signs, luni-solar periods and their application to
calendars
A calendar is a system of organizing days. This is done by giving names to periods of time, typically days, weeks, months and years. A date is the designation of a single and specific day within such a system. A calendar is also a physi ...
,
phases of the Moon
Concerning the lunar month of ~29.53 days as viewed from Earth, the lunar phase or Moon phase is the shape of the Moon's directly sunlit portion, which can be expressed quantitatively using areas or angles, or described qualitatively using the t ...
,
eclipses
An eclipse is an astronomical event that occurs when an astronomical object or spacecraft is temporarily obscured, by passing into the shadow of another body or by having another body pass between it and the viewer. This alignment of three ce ...
, star phases, terrestrial zones and geographical places, and the foolishness of making weather predictions by the stars.
[Evans, J., ''The History and Practice of Ancient Astronomy'', p. 91. Oxford University Press. (1998).]
He also wrote a commentary on Posidonius' work ''On Meteorology''. Fragments of this commentary are preserved by
Simplicius in his commentary on
Aristotle's ''Physics''.
Mathematics
Geminus also wrote extensively on
mathematics
Mathematics is an area of knowledge that includes the topics of numbers, formulas and related structures, shapes and the spaces in which they are contained, and quantities and their changes. These topics are represented in modern mathematics ...
, including a comprehensive ''Doctrine, (or Theory) of Mathematics.''
[Heath, T., A Manual of Greek Mathematics, Dover Publications. (2003).] Although this work has not survived, many extracts are preserved by
Proclus
Proclus Lycius (; 8 February 412 – 17 April 485), called Proclus the Successor ( grc-gre, Πρόκλος ὁ Διάδοχος, ''Próklos ho Diádokhos''), was a Greek Neoplatonist philosopher, one of the last major classical philosophers ...
,
Eutocius
Eutocius of Ascalon (; el, Εὐτόκιος ὁ Ἀσκαλωνίτης; 480s – 520s) was a Palestinian-Greek mathematician who wrote commentaries on several Archimedean treatises and on the Apollonian ''Conics''.
Life and work
Little is ...
, and others. He divided mathematics into two parts: ''Mental'' ( el, νοητά) and ''Observable'' ( el, αἰσθητά), or in other words,
Pure
Pure may refer to:
Computing
* A pure function
* A pure virtual function
* PureSystems, a family of computer systems introduced by IBM in 2012
* Pure Software, a company founded in 1991 by Reed Hastings to support the Purify tool
* Pure-FTPd, F ...
and
Applied. In the first category he placed
geometry
Geometry (; ) is, with arithmetic, one of the oldest branches of mathematics. It is concerned with properties of space such as the distance, shape, size, and relative position of figures. A mathematician who works in the field of geometry is c ...
and
arithmetic
Arithmetic () is an elementary part of mathematics that consists of the study of the properties of the traditional operations on numbers— addition, subtraction, multiplication, division, exponentiation, and extraction of roots. In the 19th ...
(including
number theory
Number theory (or arithmetic or higher arithmetic in older usage) is a branch of pure mathematics devoted primarily to the study of the integers and arithmetic function, integer-valued functions. German mathematician Carl Friedrich Gauss (1777 ...
), and in the second category he placed
mechanics
Mechanics (from Ancient Greek: μηχανική, ''mēkhanikḗ'', "of machines") is the area of mathematics and physics concerned with the relationships between force, matter, and motion among physical objects. Forces applied to objects r ...
,
astronomy
Astronomy () is a natural science that studies astronomical object, celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and chronology of the Universe, evolution. Objects of interest ...
,
optics
Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behaviour of visible, ultraviole ...
,
geodesy
Geodesy ( ) is the Earth science of accurately measuring and understanding Earth's figure (geometric shape and size), orientation in space, and gravity. The field also incorporates studies of how these properties change over time and equivale ...
, canonics (
musical harmony), and
logistics
Logistics is generally the detailed organization and implementation of a complex operation. In a general business sense, logistics manages the flow of goods between the point of origin and the point of consumption to meet the requirements of ...
. Long extracts of his work are also preserved by
Al-Nayrizi
Abū’l-‘Abbās al-Faḍl ibn Ḥātim al-Nairīzī ( ar, أبو العباس الفضل بن حاتم النيريزي, la, Anaritius, Nazirius, c. 865–922) was a Persian mathematician and astronomer from Nayriz, Fars Province, Iran.
He fl ...
in his commentary on
Euclid's ''Elements''.
Notes
Bibliography
* Evans, J., Berggren, J.L.
''Geminos's Introduction to the Phenomena: A Translation and Study of a Hellenistic Survey of Astronomy.''(Princeton University Press, 2006.)
External links
*
ttps://archive.today/20020623142024/http://www.tmth.edu.gr/en/aet/2/49.html Technology Museum of Thessaloniki Entry*
PDF scans of Manitius' edition of the Geminus' ''Elementa Astronomiae'' ("Elements of Astronomy") – public domain(Classical Greek with German translation)]
{{DEFAULTSORT:Geminus
Ancient Greek astronomers
Ancient Greek mathematicians
Ancient Rhodian scientists
Roman-era Rhodians
Stoic philosophers
1st-century BC Rhodians
1st-century BC writers
1st-century BC mathematicians