4.3    Additional Questions :

Answer the following questions :

1) What is orbital plane?
Ans: The axis of the earth which is an imaginary line, makes an angle of 66½0 with its orbital plane. The plane formed by the orbit is known as the orbital plane.

2) What is called as circle of illumination?
Ans: Due to the spherical shape of the earth, only half of it gets light from the sun and the other half experiences night. The circle that divides the day from the night on the globe is called circle of illumination.

3) A year is divided into how many seasons? What are they?
Ans: A year is usually divided into 4 seasons. They are summer, winter, rainy, and autumn seasons.

4) Why do seasons change?
Ans: Seasons change due to the change in the position of the earth around the sun.

Fill in the blanks:

a) A leap year has ___________ number of days.

b) The daily motion of the earth is _________ .

c) The earth travels around the sun in ____________ orbit.

d) The sun’s rays fall vertically on the tropic of ________ on 21st June .

e) Days are shorter during __________ seasons.