First Method to find position of celestial objects
Horizon System
❑ Zenith: The point above the observer on the Celestial Sphere.❑ Nadir: The Point below the observer on the Celestial Sphere.
❑ Horizon: According to the observer, the sphere which has been formed and this is called observer's sphere and the equator of this sphere is called Horizon. North and South pole of this sphere is called Zenith and Nadir respectively.
Above the head of the observer in northern hemisphere on the this sphere/observer's sphere is called Zenith. and above the head of the observer in southern hemisphere on the this sphere/observer's sphere is called Nadir.
❑ Local Meridian/ Observer’s meridians: Prime meridian in observer's sphere. Zenith+ N.C.P. + nadir + S.C.P. + zenith.
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Altitude & Azimuth
❑ Azimuth(A)= arc length NY(on horizon) , it’s varies from 0 to 180.
❑ Zenith Distance(z)= ZX=90-a.
❑ Coordinate system of horizon system=(A, a) or (A, z).
❑Horizon system is very simple system. using this system we can find the position of celestial bodies using tiny little telescope.
❑ Azimuth tells us the direction in which we can move the telescope along the equator so we can locate the aim. On the other hand altitude tells us that the telescope moves upward and downward so we can focus our aim.
Demerits of Horizon System
1. When two people observe the
same object at same time at
different location and note down
the coordinates then their
coordinates are different from
each other.
2. Earth moves from west to east.
if we consider star is fixed so, 2nd
observer has it’s own Z, Z’ and
Horizon.
3. If the position of observer changes then Z and Z’ will change. Then
Horizon will also change then Altitude and azimuth(A)) will be
also change.
Relevant link🔗 : Celestial Sphere