Question

Give reasons for the following statement :
The duration of day and night is equal everywhere on 21st March and 23rd September.

Answer 1

These are two special positions in the revolutionary course of the Earth when days and nights are equal throughout the world. They are the two equinox, the first on March 21 st and the second on September, 23 rd. Because on these two days the mid-day sun is overhead at the equator, the positions of both the hemispheres are the same in respect of the sun.