Rotation And Revolution

What is Rotation?

A rotation is a circular movement of an object around a centre of rotation. If three-dimensional objects like earth, moon and other planets always rotate around an imaginary line, it is called a rotation axis. The axis passes through the body’s centre of mass, the body is said to rotate upon itself or spin.

What is Revolution?

Revolution is often used as a synonym for rotation. However, in many fields like astronomy and its related subjects, revolution is referred to as an orbital revolution. It is used when one body moves around another while rotation is used to mean the movement around the axis. For example, Moon revolves around the Earth, and the Earth revolves around the Sun.

Rotation And Revolution

Rotation of the Earth

The spinning of the Earth around its axis is called ‘rotation’. The axis has an angle of \(23 \frac{1}{2}^{\circ }\) and is perpendicular to the plane of Earth’s orbit. Which means, Earth is tilted on its axis, and because of this tilt, the northern and southern hemispheres lean in a direction away from the Sun. The rotation of the Earth divides it into a lit-up half and a dark half, which gives rise to day and night.

Revolution of the Earth

The movement of the Earth around the Sun in a fixed path is called a revolution. The Earth revolves from west to east i.e, in the anticlockwise direction. The Earth completes one revolution around the Sun in one year or precisely in 365.242 days.

The revolution speed of the earth is 30km.s-1.

Rotation and Revolution of Planets

Planets Mean distance from the Sun in millions of kilometers Period of Revolution Period of Rotation
Mercury 57.9 88 days 59 days
Venus 108.2 224.7 days 243 days
Earth 149.6 365.2 days 23 hr, 56 min, 4 sec
Mars 227.9 687 days 24 hr, 37 min
Jupiter 778.3 11.86 years 9 hr, 55 min, 30 sec
Saturn 1,427 29.46 years 10 hr, 40 min, 24 sec
Uranus 2,870 84 years 16.8 hours
Neptune 4,497 165 years 16 hr, 11 min

Difference Between Rotation and Revolution

The table given below provides the basic differences between the rotation and revolution.

Rotation Revolution
Rotation of the Earth is its turning on its axis. Revolution is the movement of the Earth around the Sun.
The Earth takes 24 hours to complete a rotation around the Sun. The Earth takes a full year (365 days) for one complete revolution around the Sun
The Earth’s axis of rotation is tilted by 23.5 degrees. This tilt causes the different seasons of the year. The path of the Earth moving around the Sun is called an orbit. The Earth’s orbit is elliptical.

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