APOGEE, ἀπόγειος in Astronomy, that Point in the Orbit of the Sun, or a Planet, which is furthest distant from the Earth. See ORBIT and EARTH.
The Apogee is a Point in the Heavens, at the Extreme of the Line of the Apsides; in which the Sun, or a Planet, is at the greatest Distance that it can be at, from the Earth, in its whole Revolution. See APSIS, EARTH, PLANET, etc.
The opposite Point hereto, is called the Perigee. See PERIGEE.
The ancient Astronomers, regarding the Earth as the Centre of the System; chiefly considered the Apogee and Perigee: The Moderns, making the Sun the Centre, change the Apogee and Perigee for Aphelion and Perihelion. See APHELION and PERIHELION. See also SYSTEM.
The Apogee has a Motion; the Quantity of which is found by comparing two Observations thereof made at a great distance of time; converting the difference into Minutes, and dividing it by the number of Years elapsed between the two Observations. The Quotient gives the annual Motion of the Apogee——Thus, from an Observation made by Hipparchus in the Year before Christ 127, whereby the Sun’s Apogee was found 5°, 30’ of II ; and another made by Ricciolus, in the Year of Christ 1646, wherein it was found 7°, 26’, of Scorpio the annual Motion of the Apogee is found to be 1’, 2”.
Apogees of the Moon. See MOON.
Apogees of the Equant, is its farthest Distance from the Earth; or that Point where the Circumference of the Equant is intersected by the Line of the Apsides, in the remotest part of the Diameter.
So the Perigee of the Equant is the opposite Point, or the nearest part of the Diameter.
The mean Apogee of the Epicycle, is a Point where the Epicycle is cut above, by a right Line drawn from its Centre, to the Centre of the Equant, or the Point of the Epicycle most remote from the Earth. See EPICYCLE.
The Word is formed of the Greek ἀπό (apo), away, from; and γῆ (gē) or γαῖα, Earth—In the corrupt Latin, apogee sometimes signifies a Grotto, or subterraneous Vault.
