What is Rotation and Revolution?

What is Rotation and Revolution?

Imagine a line passing through its centre of mass, this imaginary line is called the axis. And our planet Earth spins around on this invisible line just like a top, and this circular movement is of an object spinning around its axis is called “The Rotation”. And due to this rotational quality of our planet, we witness day and night.

And how is that? It is because different parts of the planet are facing towards the sun or away from it. When you are located on the side where you can see the sun, and its light and heat can reach you, it’s daytime. And when the Earth spins to take you away from the sight of the sun, where it’s light and heat can’t reach you anymore, its nighttime.

And it takes 24 hours for the Earth to turn all the way around, to make a single day. If the rotation of the Earth makes a day, then what’s makes the year? The answer to this question is the revolution! Although the Earth is rotating on its axis, at the same time, it also revolves on orbits around the sun, which is called revolution. And one full orbit all the way around the sun is one revolution, and the Earth takes 365 days or precisely 365.242 days to complete a revolution that makes up a whole year.

In astronomy, the word rotation is used to mean the movement around the axis, which creates the day and night on Earth. While revolution is used when one body moves around another that makes a year in the case of our planet Earth.

The Earth is not sitting with a straight posture but its axis is actually a little tilted. Ions ago, when an object the size of Mars crashed into newly formed planet Earth. It knocked our planet over and left it tilted at an angle. And this slight tilt made one part of the Earth lean towards the sun, while the other part of it is leaning away.

And there is a great significance to this tilt. Due this angle, the solar energy reaching different parts of our planet is not considered but varies during the year. As at a particular time, the Northern Hemisphere is leaning towards the sun while the Southern is leaning away. And at other times, the Southern Hemisphere tilts towards the sun, whereas the Northern Hemisphere leans away. And this why we have different seasons and why the seasons are opposite in the Northern and Southern Hemispheres. The part of the Earth leaning towards the sun causes summer in that region. And the days are long. While the part leaning away experiences cold climate with shorter days.

Did you know, the angle made by the axis of the Earth, which is an imaginary line with the orbital plane is 66 degrees? Also, it is said that humans have made a moderate change in the Earth’s rotation period by several microseconds by accumulating vast reservoirs with trillions of tons of water.