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The zenith (UK: / ˈ z ɛ n ɪ θ /, US: / ˈ z iː n ɪ θ /) [1] [2] is the imaginary point on the celestial sphere directly "above" a particular location. "Above" means in the vertical direction opposite to the gravity direction at that location . The zenith is the "highest" point on the celestial sphere.
Diagram showing the relationship between the zenith, the nadir, and different types of horizon.Note that the zenith is opposite the nadir. The nadir [a] [b] is the direction pointing directly below a particular location; that is, it is one of two vertical directions at a specified location, orthogonal to a horizontal flat surface.
In another approach known as the horizontal coordinate system, the meridian is divided into the local meridian, the semicircle that contains the observer's zenith and the north and south points of their horizon, [1] [2] and the opposite semicircle, which contains the nadir and the north and south points of their horizon.
The azimuth is the angle formed between a reference direction (in this example north) and a line from the observer to a point of interest projected on the same plane as the reference direction orthogonal to the zenith. An azimuth (/ ˈ æ z ə m ə θ / ⓘ; from Arabic: اَلسُّمُوت, romanized: as-sumūt, lit.
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.
Seen from a superior planet, an inferior planet on the opposite side of the Sun is in superior conjunction with the Sun. An inferior conjunction occurs when the two planets align on the same side of the Sun. At inferior conjunction, the superior planet is "in opposition" to the Sun as seen from the inferior planet (see the diagram).
If the gimbal tilts to track the object from the horizon but must stop at 90 degrees, the entire telescope must pan 180 degrees to follow the object from zenith down to the opposite horizon. When there is a full-circle azimuth range and full 180-degree elevation range, all points can be reached without the need for an instantaneous 180-degree ...
In a spherical coordinate system, a colatitude is the complementary angle of a given latitude, i.e. the difference between a right angle and the latitude. [1] In geography, Southern latitudes are defined to be negative, and as a result the colatitude is a non-negative quantity, ranging from zero at the North pole to 180° at the South pole.