Earth's circumferenceEarth's circumference is the distance around Earth. Measured around the equator, it is . Measured around the poles, the circumference is . Measurement of Earth's circumference has been important to navigation since ancient times. The first known scientific measurement and calculation was done by Eratosthenes, by comparing altitudes of the mid-day sun at two places a known north–south distance apart. He achieved a great degree of precision in his computation. Treating the Earth as a sphere, its circumference would be its single most important measurement.
PosidoniusPosidonius (ˌpɒsI'doʊniəs; Ποσειδώνιος , "of Poseidon") "of Apameia" (ὁ Ἀπαμεύς) or "of Rhodes" (ὁ Ῥόδιος) (135-51 BC), was a Greek politician, astronomer, astrologer, geographer, historian, mathematician, and teacher native to Apamea, Syria. He was considered the most learned man of his time and, possibly, of the entire Stoic school. After a period learning Stoic philosophy from Panaetius in Athens, he spent many years in travel and scientific researches in Spain, Africa, Italy, Gaul, Liguria, Sicily and on the eastern shores of the Adriatic.
Degree (angle)A degree (in full, a degree of arc, arc degree, or arcdegree), usually denoted by ° (the degree symbol), is a measurement of a plane angle in which one full rotation is 360 degrees. It is not an SI unit—the SI unit of angular measure is the radian—but it is mentioned in the SI brochure as an accepted unit. Because a full rotation equals 2pi radians, one degree is equivalent to pi/180 radians. The original motivation for choosing the degree as a unit of rotations and angles is unknown.
Pappus of AlexandriaPappus of Alexandria (ˈpæpəs; Πάππος ὁ Ἀλεξανδρεύς; 290- 350 AD) was one of the last great Greek mathematicians of antiquity; he is known for his Synagoge (Συναγωγή) or Collection ( 340), and for Pappus's hexagon theorem in projective geometry. Nothing is known of his life, other than what can be found in his own writings: that he had a son named Hermodorus, and was a teacher in Alexandria. Collection, his best-known work, is a compendium of mathematics in eight volumes, the bulk of which survives.
Meridian (geography)In geography and geodesy, a meridian is the locus connecting points of equal longitude, which is the angle (in degrees or other units) east or west of a given prime meridian (currently, the IERS Reference Meridian). In other words, it is a line of longitude. The position of a point along the meridian is given by that longitude and its latitude, measured in angular degrees north or south of the Equator. On a Mercator projection or on a Gall-Peters projection, each meridian is perpendicular to all circles of latitude.
GeographerA geographer is a physical scientist, social scientist or humanist whose area of study is geography, the study of Earth's natural environment and human society, including how society and nature interacts. The Greek prefix "geo" means "earth" and the Greek suffix, "graphy", meaning "description", so a geographer is someone who studies the earth. The word "geography" is a Middle French word that is believed to have been first used in 1540.
CallimachusCallimachus (Καλλίμαχος; 310 240 BC) was an ancient Greek poet, scholar and librarian who was active in Alexandria during the 3rd century BC. A representative of Ancient Greek literature of the Hellenistic period, he wrote over 800 literary works in a wide variety of genres, most of which did not survive. He espoused an aesthetic philosophy, known as Callimacheanism, which exerted a strong influence on the poets of the Roman Empire and, through them, on all subsequent Western literature.
MouseionThe Mouseion of Alexandria (Μουσεῖον τῆς Ἀλεξανδρείας; Musaeum Alexandrium), which arguably included the Library of Alexandria, was an institution said to have been founded by Ptolemy I Soter and his son Ptolemy II Philadelphus. Originally, the word mouseion meant any place that was dedicated to the Muses, often related to the study of music or poetry, but later associated with sites of learning such as Plato's Academy and Aristotle's Lyceum.
Theon of SmyrnaTheon of Smyrna (Θέων ὁ Σμυρναῖος Theon ho Smyrnaios, gen. Θέωνος Theonos; fl. 100 CE) was a Greek philosopher and mathematician, whose works were strongly influenced by the Pythagorean school of thought. His surviving On Mathematics Useful for the Understanding of Plato is an introductory survey of Greek mathematics. Little is known about the life of Theon of Smyrna. A bust created at his death, and dedicated by his son, was discovered at Smyrna, and art historians date it to around 135 CE.
DicaearchusDicaearchus of Messana (ˌdɪkeɪˈɑːrkəs...məˈsɑːnə; Δικαίαρχος Dikaiarkhos; 370/350-post 323 BC), also written Dikaiarchos (ˈdɪkaɪɑːrk), was a Greek philosopher, geographer and author. Dicaearchus was a student of Aristotle in the Lyceum. Very little of his work remains extant. He wrote on geography and the history of Greece, of which his most important work was his Life of Greece.
