Exploring the Wonders of the Celestial Sphere: A Journey Through the Stars 🌟🌠🌃

Celestial Sphere

❑ If we assume earth at the center then we see the sky as far as we can see and then assume that there is a boundary and draw a sphere, then this sphere will be called Celestial Sphere. 

❑Celestial Equator: celestial equator of celestial sphere is parallel to earth’s equator. 

❑North Celestial Pole: point which lies vertically over the earth’s north pole.

❑South Celestial Pole: point which lies vertically below the earth’s south pole.

❑ And this surface of the sphere we assume that all celestial objects are embedded. but in reality these celestial objects are far away from each other. But these are too far from us, thus they looks likes embedded on surface of celestial sphere.

Geometry of Sphere

❑  If we cut a any sphere using a plane from it’s center then these circles are called Great circle. And plane which has not crossed the center or do not cut from the center then we get Small circle.

• FG= Great Circle

• P and Q= Poles of Great Circle

• EH= Small Circle

• PQ= Diameter of Great Circle (FG)

• CD= Arc length of Great Circle (FG)
• AB= arc length of small circle (EG)

Latitude and Longitude

❑ Latitude: West to East or East to West. It has only one Great Circle. This Great circle is Called Equator. And there are too many Small Circles. From equator, if we go north then angle is 0 to 90 and go south the 0 to -90.

❑ Longitude: North to South or South to North. it have many Great Circles and too many meridian and no small Circle. it is 0 to 360.

❑ To study any point on earth, we need coordinates. One coordinate is on Longitude and 2nd is on Latitude. 

❑ According to International Law, we consider one coordinate i.e. Longitude is from Greenwich(i.e. our prime meridian) and 2nd latitude is from equator.

❑ Similarly if we need to study of Celestial Sphere then we need a prime meridian and one equator. To study this sphere we have two coordinates system.

❑ Then we have 2 system. 1. Horizon system and 2. Equatorial system.