Question

Why is the length of a sidereal day and a solar day on earth so similar?

Answer 1

Solar time is based on the movement of the sun in the sky (time taken by the sun to appear in the same meridian in the sky) while the sidereal time is the time respect to motion of fixed stars in the sky due to the rotation of the earth. Sidereal time depends on the rotation of the earth on its own axis while the solar time is based on the earth orbiting on around the sun this creates the difference between the solar time and the sidereal day of about 4 minutes. The similarity is that both the earth rotation and the orbiting of the earth around the son takes place in same direction (anticlockwise direction). In addition the sun is considered to be star.