Question

Exact time taken by earth to complete one revolution

Answer 1

The Earth takes 365 ¼ days to revolve around the Sun. This is known as one Earth year.

Answer 2

Earth rotates once in about 24 hours with respect to the Sun, but once every 23 hours, 56 minutes, and 4 seconds with respect to the stars (see below). Earth's rotation is slowing slightly with time; thus, a day was shorter in the past.