Chapter 2, Problem 1E

From where on Earth could you observe all of the stars during the course of a year? What fraction of the sky can be seen from the North Pole?

To determine

Location on the Earth where one can observe all the stars duringa year and the fraction of the sky that can be seen from the North Pole.

Answer to Problem 1E

From the equator, onecan observe all the stars during a year and half of the sky can be seen from the North Pole.

Explanation of Solution

Introduction:

When earth rotates about its axis in a day and revolves about the Sun, the part of sky changes that can be seen. Stars visible in the North Pole will not be visible in the South Pole. Celestial sphere is an imaginary sphere centered around the earth on which all the celestial bodies are projected.

From any location on the equator, all the stars in the sky will be visible at one time or another throughout the year. From any other latitude except equator, at least a portion of the sky will be permanently out of sight. 

From the North Pole, only half the sky is visible. Suppose a man is standing at the north pole. He would be able to see everything in northern celestial hemisphere, but he would not be able to see anything in southern celestial hemisphere.