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Technical Terms

Longitude : Distance of place, east or west of a given meridian distance in degrees from the vernal equinox on the ecliptic.

Latitude : The distance of place north or south from the equator, measured in degrees from the meridian or the angular distance of a celestial body above the plane of the ecliptic.
Equinox : The bigger circle of the ecliptic intersects the bigger circle of the celestial equator. Each year this happens twice, i.e. on the 21st March & 23rs Sept. when the durations of day & night are equal. On the 21st March it is called vernal equinox, whereas 23rd sept. autumnal equinox.
Equator : A great circle, drawn east to west, Divides the celestial sphere into two equal parts which are known as Northern & Southern  hemisphere. The sun remains in northern hemispehre form 21st March to 23rd Sept. while from 24th sept to 20th march in southern hemisphere.
Meridian : Pertaining to the mid-day an imaginary circle passing through the poles of  the heavens and the zenith of the spectator which the sun crosses at mid-day.
Azimuth : The arc of the horizon between the meridian of a place and a vertical circle passing through any celestial body. This is calculated towards west throuth 360 degrees in horizontal plane
Altitude : This is the distance of the heavenly body vertically above the horizon, it is calculated through 90 degrees.
Eclipse : An obstruction of one of the heavenly bodies by the interposition of another either between it and the spectator or between it and the sun. In other words to hide a luminous body wholly or in part.
Ecliptic : It is the name given to great circle of the heavens round which the sun seems to travel from west to east during the year. A great circle on the globe corresponding to the celestial ecliptic.
Declination : Distance from the celestial equator, or the angular distance of a heavenly body north or south of the equator, measured along the the great circle passing through the body observed and the pole.