Earth’s orbit is an ellipse with eccentricity 0.0167. Thus, the earth’s distance from the sun and speed as it moves around the sun varies from day to day. This means that the length of the solar day is not constant throughout the year. Assume that earth’s spin axis is normal to its orbital plane and find out the length of the shortest and the longest day. A day should be taken from noon to noon. Does this explain the variation of the length of the day during the year?

Solution:

Velocity of the earth at perigee is given as

Velocity of the earth at apogee is given as

Angular velocity of the earth at perihelion is given as

Angular velocity of the earth at aphelion is given as

So,

ꞷ is the mean angular speed having value

As a result, it may be concluded that this does not account for the actual fluctuation in day length over the year.