Astronomy & Astrophysics: Ancient & Early Astronomy

From Astronomy Encyclopedia
Astronomical treatise composed in c.AD 140 by Ptolemy. It summarizes the astronomy of the Graeco-Roman world and contains a star catalogue and rules for calculating future positions of the Moon and planets according to the Ptolemaic System.

Study of the relative position of the planets and stars in the belief that they influence events on Earth. A strongly held belief in ancient Babylon, astrology spread to the Mediterranean world, and was widely used by the Greeks and Romans.

System of reckoning time for the practical purpose of recording past events and calculating dates for future plans. The calendar is based on noting ordinary and easily observable natural events, the cycle of the sun through the seasons with equinox and solstice, and the recurrent phases of the moon.

From The American Heritage Science Dictionary
In Ptolemaic cosmology, a small circle representing a temporary adjustment to the position of a planet as it orbits the Earth.

From The Penguin English Dictionary
A fixed projecting part that casts a shadow on the face of a sundial, indicating allowing the time to be told.

From The Columbia Encyclopedia
Historically the most influential of the geocentric cosmological theories, i.e., theories that placed the earth motionless at the center of the universe with all celestial bodies revolving around it (see cosmology).

From The Hutchinson Unabridged Encyclopedia
Prehistoric megalith. The circles were built with standing stones, usually on level ground. Many are now partly fallen or incomplete, the stones having been removed for building.

Instrument that indicates the time of day by the shadow, cast on a surface marked to show hours or fractions of hours, of an object on which the sun's rays fall.

From The Hutchinson Unabridged Encyclopedia
Arabian scientist. He was the author of the Kitab al-Manazir/Book of Optics, translated into Latin as Opticae thesaurus (1572). For centuries it remained the most comprehensive and authoritative treatment of optics in both East and West.

Greek mathematician, physicist, and inventor. He is famous for his work in geometry (on the circle, sphere, cylinder, and parabola), physics, mechanics, and hydrostatics.

From Science in the Ancient World: An Encyclopedia
Aristarchus of Samos was a mathematician who was the first human to argue that the sun, not the earth, was the center of the universe. Aristarchus was a theorist more than an empiricist.

From Astronomy Encyclopedia
Indian mathematician and astronomer who wrote three astronomical treatises, only one of which, the Āryabhatīya (AD 499), survives.

From Chamber's Biographical Dictionary
Born in Wan (Nanyang), he was the astronomer royal at the court of the later Han emperors. Although none of his actual works has survived there are detailed accounts extant of several of his inventions.

From Science in the Ancient World: An Encyclopedia
Eudoxus, Pythagorean and student of Plato, was an astronomer, mathematician, and physicist. He wrote Phaenomena, one of the seminal statements from the ancient world on astronomy.

From Science in the Ancient World: An Encyclopedia
Heraclides was an astronomer of note and the first known to speculate that at least some planets orbit the sun. He was a student of the Academy and was influenced by both Plato and Aristotle.

From Astronomy Encyclopedia
Greek astronomer, geographer and mathematician who made observations from Nicea (in what is now modern Turkey), Alexandria, Egypt and the Greek island of Rhodes.

From Brewer's Dictionary of Phrase and Fable
The Persian poet, astronomer and mathematician lived at Nishapur, where he died at about the age of 50 in about ad 1123.

Greek astronomer, mathematician, and geographer. His Geography was the standard geographical textbook until the discoveries of the 15th century.

From The Columbia Encyclopedia
Instrument probably used originally for measuring the altitudes of heavenly bodies and for determining their positions and movements.

From The Columbia Encyclopedia
First modern European theory of planetary motion that was heliocentric, i.e., that placed the sun motionless at the center of the solar system with all the planets, including the earth, revolving around it. Copernicus developed his theory in the early 16th cent. from a study of ancient astronomical records.

From Astronomy Encyclopedia
Model of the Solar System in which the Sun is at the centre and the planets revolve around it. A heliocentric theory was proposed by the Greek astronomer ARISTARCHUS in the 3rd century BC, but it seemed counter-intuitive at the time and was not widely adopted.

From The Columbia Encyclopedia
Three mathematical statements formulated by the German astronomer Johannes Kepler that accurately describe the revolutions of the planets around the sun.

From Astronomy Encyclopedia
Early instrument used for measuring declination. It consists of a graduated circle fixed to a wall (in Latin, murus) orientated north-south.

From Collins Dictionary of Astronomy
The first reflecting telescope to be built, developed in about 1670 by Isaac Newton from the ideas of Zucchi and Gregory: Newton turned his attention to reflecting telescopes because he thought (wrongly) that there was no way in which the chromatic aberration of refracting telescopes could be corrected.

From Astronomy Encyclopedia
Telescope that utilizes the refraction of light through lenses to form images of distant objects. In its simplest form, a refracting telescope consists of two lenses, an objective, and an eyepiece.

Instrument for measuring the altitude of the sun or another celestial body; such measurements can then be used to determine the observer's geographical position or for other navigational, surveying, or astronomical applications.

From Dictionary of Astronomy
The law of gravitation set out by Newton and applying to every object in the universe. It states that every body in the universe exerts an attraction on every other, proportional to the product of their masses (their masses multiplied together) divided by the square of the distance between them.

Great Italian astronomer, mathematician, and physicist.

From Astronomy Encyclopedia
Islamic Turkish ruler of Maverannakhr (now Uzbekistan) and astronomer, whose name means ‘great prince’; his real name was Muhammad Taragi ibn Shah-Rukh ibn-Timur. In 1420 Beg built a madrasa (university) equipped with a three-story observatory at Samarkand.

Danish astronomer, sometimes known by his first name only, who is most noted for his remarkably accurate measurements of the positions of stars and the movements of the planets.

French astronomer, born in Italy. He discovered (1675) Cassini's division, the gap that divides Saturn's rings into two parts, and four of Saturn's moons.

Polish astronomer who promulgated the now accepted theory that the earth and the planets move about the sun (the Copernican system).

English mathematician, physicist, and astronomer who not only identified the comet later to be known by his name, but also compiled a star catalogue, detected stellar motion using historical records, and began a line of research that – after his death – resulted in a reasonably accurate calculation of the astronomical unit.

German-born English astronomer and musician. He took up astronomy in the 1770s, making his own telescopes and mirrors.

Dutch physicist and astronomer who discovered Saturn's rings (1655), pioneered the use of pendulums in clocks (1657), and formulated Huygens' principle.

German astronomer who combined great mathematical skills with patience and an almost mystical sense of universal harmony.

From The Hutchinson Dictionary of Scientific Biography
French astronomer whose work on the discovery of comets led to a compilation of the locations of nebulae and star clusters - the Messier catalogue - that is still of some relevance 200 years later.

English mathematician and scientist who invented differential calculus and formulated the theory of universal gravitation.

From Chambers Biographical Dictionary
English mathematician. Born probably in Halifax, West Yorkshire, he is said to have studied at Oxford and taught mathematics at Paris, where he died in 1244 or 1256.

From The Columbia Encyclopedia
Pope (999–1003), a Frenchman (b. Auvergne) named Gerbert; successor of Gregory V. In his youth he studied at Muslim schools in Spain and became learned in mathematics and astronomy.