Orbital revolution

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Saturn orbit

Orbital revolution is the movement of a planet around a star, or a moon around a planet. For example, the Earth revolves around the Sun, and the Moon revolves about the Earth.

Planets and moons revolve in elliptical orbits. One orbital revolution of a planet takes one year, while a revolution of the Moon takes a month.

Usage[change | change source]

Astronomers usually use different words for the orbit of a planet around a star, and for the spin of a planet about its own axis. The motion in an orbit is called revolving, while the spin of a planet is called rotating. For instance, the Earth revolves around the Sun completing one revolution in one year, and it rotates about its axis completing one rotation in one day. But either word can be used.