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Angular distance or angular separation is the measure of the angle between the orientation of two straight lines, rays, or vectors in three-dimensional space, or the central angle subtended by the radii through two points on a sphere.
The ground-based long-distance observations cover the Earth's landscape and natural surface features (e.g. mountains, depressions, rock formations, vegetation), as well as manmade structures firmly associated with the Earth's surface (e.g. buildings, bridges, roads) that are located farther than the usual naked-eye distance from an observer.
By subtracting this from 90°, he would find that the zenith distance is 90°, which is his latitude. Observer C at the same time is at latitude 20°N on the same meridian, i.e. on the same longitude as Observer A. His measured altitude would be 70°, and subtracting this from 90° gives a 20° zenith distance, which in turn is his latitude. In ...
Azimuth is measured eastward from the north point (sometimes from the south point) of the horizon; altitude is the angle above the horizon. The horizontal coordinate system is a celestial coordinate system that uses the observer's local horizon as the fundamental plane to define two angles of a spherical coordinate system: altitude and azimuth.
Geodetic latitude and geocentric latitude have different definitions. Geodetic latitude is defined as the angle between the equatorial plane and the surface normal at a point on the ellipsoid, whereas geocentric latitude is defined as the angle between the equatorial plane and a radial line connecting the centre of the ellipsoid to a point on the surface (see figure).
Finding the latitude requires measuring the vertical angle (altitude) of X from the horizon using a sextant, the declination of X from a reference book, and a set of sight reduction Tables. The sun, moon, and planets move relative to the celestial sphere, but only the stars' hour angles change with the rotation of the earth, completing a full ...
The projection is reasonably accurate near the equator. Scale at an angular distance of 5° (in latitude) away from the equator is less than 0.4% greater than scale at the equator, and is about 1.54% greater at an angular distance of 10°. • The projection is reasonably accurate near the central meridian.
Hence the distance is greatest when looking directly away from the Sun along the horizon in the east, and lowest along the horizon in the west. The bottom plot in the figure to the left represents the angular distance from the observed pointing to the zenith, which is opposite to the interior angle located at the Sun.