Search results
Results from the WOW.Com Content Network
This glossary of astronomy is a list of definitions of terms and concepts relevant to astronomy and cosmology, their sub-disciplines, and related fields. Astronomy is concerned with the study of celestial objects and phenomena that originate outside the atmosphere of Earth. The field of astronomy features an extensive vocabulary and a ...
The apsides refer to the farthest (2) and nearest (3) points reached by an orbiting planetary body (2 and 3) with respect to a primary, or host, body (1). An apsis (from Ancient Greek ἁψίς (hapsís) 'arch, vault'; pl. apsides / ˈ æ p s ɪ ˌ d iː z / AP-sih-deez) [1] [2] is the farthest or nearest point in the orbit of a planetary body about its primary body.
Apogee Books, an imprint of Canadian publishing house Collector's Guide Publishing; Apogee Electronics, a manufacturer of digital audio hardware systems; Apogee Software, a video game publisher and developer now known as 3D Realms; Apogee Entertainment, a video game publisher that acquired the rights to the name and logo from 3D Realms
In astronomy, the altitude in the horizontal coordinate system and the zenith angle are complementary angles, with the horizon perpendicular to the zenith. The astronomical meridian is also determined by the zenith, and is defined as a circle on the celestial sphere that passes through the zenith, nadir, and the celestial poles .
The lunar orbit's major axis – the longest diameter of the orbit, joining its nearest and farthest points, the perigee and apogee, respectively – makes one complete revolution every 8.85 Earth years, or 3,232.6054 days, as it rotates slowly in the same direction as the Moon itself (direct motion) – meaning precesses eastward by 360°.
Astrophysicist Fred Espenak uses Nolle's definition but preferring the label of full Moon at perigee, and using the apogee and perigee nearest in time rather than the greatest and least of the year. [13] Wood used the definition of a full or new moon occurring within 24 hours of perigee and also used the label perigee-syzygy. [7]
The line of apsides of an ellipse connects point 2 and 3 ().An apse line, or line of apsides, is an imaginary line defined by an orbit's eccentricity vector.It is strictly defined for elliptic, parabolic, and hyperbolic orbits.
The argument of periapsis (also called argument of perifocus or argument of pericenter), symbolized as ω (), is one of the orbital elements of an orbiting body. . Parametrically, ω is the angle from the body's ascending node to its periapsis, measured in the dire