The Earth’S Revolution

Introduction

The phenomenon where the Earth moves around the Sun in a fixed path is known as Earth’s revolution. Do you know that the speed with which our Earth revolves around the Sun ranges from 29.29 to 30.29 km/s? And with this speed to complete one Earth’s revolution, it takes one year! The fixed path or orbit in which the Earth revolves around the Sun is elliptical. Therefore, there are times when the Earth is closest to the Sun and similarly farthest also. During this revolution around the Sun, the Earth covers approximately 150 million kilometres.

The Earth’s Revolution:

The Earth revolves around the Sun in its fixed elliptical orbit, and this phenomenon is what we call Earth’s revolution. The Earth completes one revolution in 365 days, 6 hours and 9 minutes precisely, concerning the stars. The gravitational pull of the Sun keeps the Earth moving in its fixed orbit.

The Earth’s Revolution: Speed of Revolution, 

According to the National Aeronautics and Space Administration (NASA), the speed with which the Earth revolves around the Sun ranges from 29.29 to 30.29 kilometres per second. One can only imagine how fast this pace is. Even with this speed, it takes more than 365 days to complete one revolution by the Earth. 

The Earth’s Revolution: The path or the axis of the Earth’s Revolution

The path or the axis of the Earth in which it revolves or orbits around the Sun is elliptical. Naturally, there are instances where the Earth reaches closest to the Sun and is farthest from the Sun as well. The Earth is closest to the Sun at perihelion, and in aphelion, it is the farthest from the Sun. Our Earth’s revolution takes place at a slower pace when at aphelion, whereas it moves faster when at perihelion. 

The Earth’s Revolution: Movements of the Earth

Earth’s motions and Earth’s movements are often synonymously used. There are majorly two types of movements of the Earth, which are as follows:

• The Earth rotates around its polar axis and this movement is called the Earth’s rotation. The axis around which the Earth’s rotation takes place is an imaginary line passing through its centre from the north to the south pole. The Earth rotates exactly 360° in one mean solar or Sidereal day. The time taken to complete one rotation is 23 hrs 56 min 4.0909 seconds precisely, which completes a day
• The second type of motion is the Earth’s revolution, where the Earth moves around the sun in a fixed elliptical path

The Earth’s Revolution: The axis of the Earth’s Rotation

Imagine a line passing vertically through the centre of our Earth, from the north pole to the south pole. This imaginary line is the polar axis of our Earth. Spinning movement around this axis is responsible for the Earth’s rotation. The polar axis is only for the Earth’s rotation. The the axis of the earth’s revolution is different and is discussed previously in this article.

The Earth’s Revolution: Motions of the Earth, UPSC Notes

The motions of the Earth can be broadly classified into the following: 

• Earth’s Rotation: The Earth rotates 360° about its polar axis to complete one Earth’s rotation
• Earth and Moon orbiting around a common Gravitational Centre: The Earth and Moon together form a system that orbits around a common gravitational centre, that is, the Sun
• Earth’s Revolution: The Earth revolves around the sun about its elliptical axis. It requires one year to complete a single Earth’s revolution.
• The motion acting due to the revolution of the Sun and Earth around the gravitational centre of the solar system: The weights of the planets Earth and Jupiter influence the Sun and cause a wobbling motion. However, this wobble is very slow but detectable with time. It can also be concluded that the Earth is revolving around a Sun that is slowly wobbling
• Equinoctial Precession: The swinging motion by which a smooth change in the direction of the axis of the earth takes place. An equinoctial precession takes 26,000 years to occur
• Sun’s Revolution Around the Galaxy Once in Every 250 Million Years: The Sun revolves around the Milky Way Galaxy once every 250 million years. This, in turn, influences the motion of the Earth naturally
• The movement of the Galaxy around the Universe: Our solar system is dynamic. The speed with which the Milky Way Galaxy and the Andromeda Galaxy are approaching each other is about 400 km/s
• Polar Variation due to Earth: The wobbling motion of the Earth causes the positions of the North and the South poles to dislocate and vary by 3 to 15 m. As a result, the Global Positioning System (GPS) readings are affected

The Earth’s Revolution: Relation with seasons

Now that we know what is a revolution of the Earth, we will now learn how seasons are related to the Earth revolution. The Earth has seasons as it is slightly tilted at an angle of 23.5° about its axis, rather than being vertically straight along its polar axis. 

The Earth’s Revolution: Relation with a length of day and night

The Earth has two primary motions, which are rotation and revolution. These two movements are primarily responsible for all the life cycles of all living organisms on this Earth. We have a regular day and night cycle as the Earth rotates or spins about its imaginary line, known as its polar axis. One entire rotation takes 24 hours to get completed. As different parts of the world face the sun because of Earth’s rotation; daytime is experienced. Similarly, as those parts face away from the Sun, nighttime is experienced. 

Conclusion

All the main points required to complete the topic of the Earth’s revolution have been covered in this article. We have seen what the revolution of the Earth is. We have understood the speed and the axis of the Earth’s revolution. Furthermore, we have also focused on the different motions of our Earth and the relation of Earth’s revolution with natural phenomena like the occurrence of seasons, how the length of day and night vary, and so on.