Revolution, in an astronomical context, refers to the movement of one celestial body around another. For example, the Earth completes a revolution around the Sun approximately every 365.25 days, which defines a year. This movement is elliptical, meaning the distance between the Earth and the Sun varies throughout the year. Rotation, on the other hand, is the spinning of a celestial body around its own axis. The Earth rotates once approximately every 24 hours, resulting in the cycle of day and night. This rotation is responsible for the apparent movement of the Sun across the sky.