Chapter 1, Problem 1QFR

(1.1) What is the celestial sphere? What are the celestial equator and the ecliptic?

To determine

The celestial sphere, celestial equator, and the ecliptic.

Answer to Problem 1QFR

The celestial sphere is an imaginary sphere that contains Earth at its center and all celestial objects inside are seen inside surface of the sphere including yourself when it is seen from space and the celestial equator is the equator which is above the Earth’s equator. The line or path that the Sun trace across the celestial sphere is called ecliptic.

Explanation of Solution

Celestial sphere; in this sphere all celestial objects are seen on the inner surface of the sphere and all are at same distances from the center of the Earth but actually they are positioned at different distances from Earth and this sphere rotates about same axis of Earth rotates.

Imagine that when we are seeing the night sky, all stars are seen on the dome of the sphere and this dome is stretched to the horizon, usually here the upper half of the sphere are seen (north celestial sphere) when we are in above the equator and lower half of the celestial sphere (south celestial sphere) seen when we are in below the equator.

Celestial equator is an equator where the celestial sphere and the plane of the terrestrial equator intersects.

On the celestial sphere, the path traced by the Sun as it moves through the constellation is called ecliptic.

Conclusion:

Therefore, the celestial sphere is a sphere which spins the celestial pole that lies above the Earth’s pole and celestial equator is the equator of the celestial sphere, also the path traces by the Sun on the celestial sphere is called ecliptic.