Definition of apsis Apsis

ap•sis

We found 11 definitions of apsis from 8 different sources.

What does apsis mean?

Noun
apsis - a domed or vaulted recess or projection on a building especially the east end of a church; usually contains the altar
		apse
		niche, recess (ecology) the status of an organism within its environment and community (affecting its survival as a species)
		church building, church a place for public (especially Christian) worship; "the church was empty"

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apsis (Noun)
A recess or projection, with a dome or vault, at the east end of a church; an apse.
apsis (Noun)
Either of the points in the elliptical orbit of a planet or comet where it is closest or furthest from the sun; perihelion or aphelion; an apside.

apsis (n.)
One of the two points of an orbit, as of a planet or satellite, which are at the greatest and least distance from the central body, corresponding to the aphelion and perihelion of a planet, or to the apogee and perigee of the moon. The more distant is called the higher apsis; the other, the lower apsis; and the line joining them, the line of apsides.
apsis (n.)
In a curve referred to polar coordinates, any point for which the radius vector is a maximum or minimum.
apsis (n.)
Same as Apse.

apsis
Point of greatest or least distance of the elliptical orbit of an astronomical object from the center of mass of the system, e. g. perihelion or aphelion

apsis
ap′sis, n. one of the two extreme points in the orbit of a planet, one at the greatest, the other at the least distance from the sun: one of the two points in the orbit of a satellite—one nearest to, the other farthest from, its primary; corresponding, in the case of the moon, to the perigee and apogee:—pl. Apsides (ap′si-dēz).—adj. Ap′sidal. [L. apsis—Gr. hapsis, a connection, an arch—hapt-ein, to connect. See Apt.]

apsis
Either of the two points in planetary orbits where they are at the greatest and the least distance from the sun, and are termed higher or lower accordingly. The two are joined by a diameter called the line of the apsides.

In astronomy, an apsis, plural "apsides" (IPA: //) is the point of greatest or least distance of the elliptical orbit of an astronomical object from its center of attraction, which is generally the center of mass of the system.

The point of closest approach is called the periapsis or pericentre and the point of farthest excursion is called the apoapsis (Greek από, "from", which becomes απ before a vowel, and αφ before rough breathing), apocentre or apapsis (the latter term, although etymologically more correct, is much less used). A straight line drawn through the periapsis and apoapsis is the "line of apsides". This is the major axis of the ellipse, the line through the longest part of the ellipse.

Similar words are used to identify the body being orbited. The most common are perigee and apogee, referring to orbits around the Earth, and perihelion and aphelion, referring to orbits around the Sun (Greek ‘ήλιος "hēlios" sun). During the Apollo program, the terms pericynthion and apocynthion were used when referring to the moon.