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. |