Prithvi Goal Kyu Hai: Know why the Earth is round, flat at the poles and raised at the equator. Gravity, rotation and know what science says about it.
Why Is Earth Round: We are often told and taught that the Earth is round. According to science, the Earth is not perfectly round. It is slightly flat at the poles (North and South Pole) and slightly raised near the middle i.e. the Equator. This shape is called Oblate Spheroid. Now the question arises, why is the shape of the Earth like this? The answer lies in gravity and the rotation of the Earth.
Why did the earth become round?
1. Gravity pulls everything towards the center
When the Earth formed billions of years ago, it was a giant ball of hot gas, dust and molten rocks. At that time gravity started pulling matter from every direction towards its center. When a very large body gets equal gravity or pressure (invisible force) from all sides, it gradually starts becoming spherical. This is the reason why the Earth, the Sun and most of the major planets appear almost round. For example, if we press a lump of wet soil from all directions with our hands, it gradually starts taking a round shape. This is exactly how gravity created the Earth.
2. Then why is the Earth not completely round?
The Earth makes one revolution on its axis in approximately 24 hours. Due to this rotation, a slight outward force (Centrifugal Effect) is generated near the equator. Because of this, the Earth became slightly convex in the middle and slightly flat at the poles. That means the shape of the Earth is certainly round, but not completely round.
3. What would happen if the Earth were square?
If the shape of the Earth were square or of some irregular shape, then gravity would not be equal everywhere. Due to this, the sea, rivers and atmosphere do not remain stable. In many places it would have been difficult to create favorable conditions for life. This is the reason the natural shape of the larger planets is almost round.
4. Why do we see the Earth as flat?
The size of the Earth is very huge. Its diameter is approximately 12,742 kilometers. Therefore when we stand on the ground, its curvature is not visible to our eyes. For example, if you stand in the middle of a big stadium, its entire circumference is not visible at a glance. Similarly, the Earth is so big that we do not feel its rotation.
5. How did scientists know that the Earth is round?
It has become clear from the photographs taken by satellites, spacecraft and astronauts that the Earth is round. Apart from this, thousands of years ago also people had predicted it from many signals, such as-
- The gradual disappearance of the ship from the bottom of the sea.
- Earth’s round shadow visible on the Moon during a lunar eclipse.
- Difference in sun shade at different places.
Some interesting facts related to earth
- The diameter of the Earth is approximately 12,742 kilometers.
- The circumference of the Earth at the equator is approximately 40,075 kilometers. Because of this the size of the Earth is huge.
- There is a distance of about 43 kilometers between the poles and the equator. The diameter of the equator is about 43 km greater than that of the poles, so the Earth is not perfectly round.
- The first complete photograph of Earth was taken in 1972. The Blue Marble photo taken during NASA’s Apollo 17 mission showed the entire world the true form of the Earth.
- All the major planets in the solar system are approximately round.
Content Sources: NASA, European Space Agency, National Geographic Society, Encyclopaedia Britannica, United States Geological Survey.