Search results
Results From The WOW.Com Content Network
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 solar zenith angle is the zenith angle of the sun, i.e., the angle between the sun’s rays and the vertical direction.It is the complement to the solar altitude or solar elevation, which is the altitude angle or elevation angle between the sun’s rays and a horizontal plane.
The geometric center of the Earth, i.e. the arithmetic mean position of all points within the oblate spheroid that is the precise shape of the Earth. geocentric With reference to, or pertaining to, the geometric center of the Earth; [14] centered upon the Earth, e.g. a geocentric orbit. geocentric zenith
In astronomy, coordinate systems are used for specifying positions of celestial objects (satellites, planets, stars, galaxies, etc.) relative to a given reference frame, based on physical reference points available to a situated observer (e.g. the true horizon and north to an observer on Earth's surface). [1]
In astronomy, the meridian is the great circle passing through the celestial poles, as well as the zenith and nadir of an observer's location. Consequently, it contains also the north and south points on the horizon, and it is perpendicular to the celestial equator and horizon.
Definition [ edit ] This celestial coordinate system divides the sky into two hemispheres : The upper hemisphere, where objects are above the horizon and are visible, and the lower hemisphere, where objects are below the horizon and cannot be seen, since the Earth obstructs views of them.
Since the concept of being below is itself somewhat vague, scientists define the nadir in more rigorous terms. Specifically, in astronomy, geophysics and related sciences (e.g., meteorology), the nadir at a given point is the local vertical direction pointing in the direction of the force of gravity at that location.
In astronomy, astrology, and geodesy, the prime vertical or first vertical [1] is the vertical circle passing east and west through the zenith of a specific location, and intersecting the horizon in its east and west points.