Coordinate System Flashcards
Altitude-Azimuth Coordinate System
Method describing position of object in sky in terms of two angles—altitude above horizon and azimuth which is clockwise from north.
Altitude
Angle measured from from the horizon to the object along a great circle that passes through the object and the point on the celestial sphere directly above observer.
Zenith
Point directly above observer
Zenith Distance
Angle measured from the zenith to the object.
z + h = 90 degrees
Azimuth
The angle measured along horizon eastward from north to the great circle used for measure of altitude.
Meridian
Great circle passing through observer’s zenith and intersecting horizon due North and South.
Ecliptic
Great circle representing Sun’s apparent path during the year.
Celestial Equator
(Imaginary) kind that extends from Earth’s equator into celestial sphere.
Vernal Equinox
Point on which the sun’s path crosses the celestial equator from South to North.
Autumnal Equinox
Point on which the sun’s path crosses the celestial equator from North to South.
Summer Solstice
Point in which Sun reaches its most Northern excursion.
Winter Solstice
Point in which Sun reaches its most Southern excursion.
Equatorial Coordinate System
Based on the latitude-longitude system of Earth but does not participate in Planet’s rotation.
Declination
Equivalent of latitude and is measured in degrees north or south of celestial equator.
Right Ascension
Analogous to longitude and is measured eastward along the celestial equator from vernal equinox it its intersection with object’s hour circle.
