Search results
Results From The WOW.Com Content Network
The zenith (UK: / ˈ z ɛ n ɪ θ /, US: / ˈ z iː n ɪ θ /) [1] 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.
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.
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.
The reference plane is perpendicular (orthogonal) to the zenith direction, and typically is designated "horizontal" to the zenith direction's "vertical". The spherical coordinates of a point P then are defined as follows: The radius or radial distance is the Euclidean distance from the origin O to P.
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.
The point on the celestial sphere exactly opposite from the zenith. Thus, where the zenith is directly above an observer, the nadir is underfoot. The zenith and nadir form the two poles of the horizon line. naked eye. Also bare eye or unaided eye.
The subsolar point on a planet or a moon is the point at which its Sun is perceived to be directly overhead (at the zenith); [1] that is, where the Sun's rays strike the planet exactly perpendicular to its surface. The subsolar point occurs at the location on a planet or a moon where the Sun culminates at the location's zenith. This occurs at ...
A meridian contact is the moment when the object contacts the observer's meridian, i.e. the imaginary line running north–south and through the zenith, nadir, and celestial poles. This is usually done with the equinox Sun at solar noon to determine the observer's latitude, but can be done with any celestial object.