Menelaus of Alexandria

Menelaus of Alexandria (c. 70–140 CE) was a Greek^[1] mathematician and astronomer, the first to recognize geodesics on a curved surface as natural analogs of straight lines.

Life and Works

Although very little is known about Menelaus's life, it is supposed that he lived in Rome, where he probably moved after having spent his youth in Alexandria. He was called Menelaus of Alexandria by both Pappus of Alexandria and Proclus, and a conversation of his with Lucius, held in Rome, is recorded by Plutarch.

Ptolemy (2nd century CE) also mentions, in his work Almagest (VII.3), two astronomical observations made by Menelaus in Rome in January of the year 98. These were occultations of the stars Spica and Beta Scorpii by the moon, a few nights apart. Ptolemy used these observations to confirm precession of the equinoxes, a phenomenon that had been discovered by Hipparchus in the 2nd century BCE.

Sphaerica is the only book that has survived, in an Arabic translation. Composed of three books, it deals with the geometry of the sphere and its application in astronomical measurements and calculations. The book introduces the concept of spherical triangle (figures formed of three great circle arcs, which he named "trilaterals") and proves Menelaus' theorem (an extension to spherical triangles of a previously known result). It was later translated by the sixteenth century astronomer and mathematician Francesco Maurolico.

The lunar crater Menelaus is named after him.

Bibliography

The titles of a few books by Menelaus have been preserved:

On the calculation of the chords in a circle, composed of six books
Elements of geometry, composed of three books, later edited by Thabit ibn Qurra
On the knowledge of the weights and distributions of different bodies
He may also have written a star catalogue.

Notes

^ Encyclopaedia Britannica "Greek mathematician and astronomer who first conceived and defined a spherical triangle (a triangle formed by three arcs of great circles on the surface of a sphere)."

References

Ivor Bulmer-Thomas. "Menelaus of Alexandria." Dictionary of Scientific Biography 9:296-302.

External links

Menelaus of Alexandria
Menelaus' Sphaerica Halley's Latin Translation from the Arabic and Hebrew Versions (PDF) 1758 A.D.

[1] Encyclopaedia Britannica "Greek mathematician and astronomer who first conceived and defined a spherical triangle (a triangle formed by three arcs of great circles on the surface of a sphere)."

[1]

v t e Ancient Greek astronomy
Astronomers	Aglaonice Agrippa Anaximander Andronicus Apollonius Aratus Aristarchus Aristyllus Attalus Autolycus Bion Callippus Cleomedes Cleostratus Conon Eratosthenes Euctemon Eudoxus Geminus Heraclides Hicetas Hipparchus Hippocrates of Chios Hypsicles Menelaus Meton Oenopides Philip of Opus Philolaus Posidonius Ptolemy Pytheas Seleucus Sosigenes of Alexandria Sosigenes the Peripatetic Strabo Thales Theodosius Theon of Alexandria Theon of Smyrna Timocharis
Works	Almagest (Ptolemy) Catasterismi (Eratosthenes) On Sizes and Distances (Hipparchus) On the Sizes and Distances (Aristarchus) On the Heavens (Aristotle)
Instruments	Antikythera mechanism Armillary sphere Astrolabe Dioptra Equatorial ring Gnomon Mural instrument Triquetrum
Concepts	Callippic cycle Celestial spheres Circle of latitude Counter-Earth Deferent and epicycle Equant Geocentrism Heliocentrism Hipparchic cycle Inferior and superior planets Metonic cycle Octaeteris Solstice Spherical Earth Sublunary sphere Zodiac
Influences	Babylonian astronomy Egyptian astronomy
Influenced	Medieval European science Indian astronomy Medieval Islamic astronomy