You may have heard that shape of the Earth is spherical. But are you sure that it is really spherical? The land beneath us looks quite flat. Think of at least one piece of evidence to show that the Earth is spherical. One such evidence, which was proposed more than 2300 years ago, is given in one of the later lessons. Of course, now we have photographs of the Earth taken from space, but we could fly the space-crafts only after knowing that the Earth is round!
If the Earth is spherical, why does it appear flat to us?
That is because it is too big! You may notice that a piece of a round flask looks almost flat.
Something similar thing is happening here. In Figure 1, as the circle becomes bigger, its rim appears more flat. Doesn't a portion of a football appear more flat than a portion of a ping- pong ball that is of the same size? You may know the rule in geometry that the curvature reduces as the radius increases.
Figure 1: Curvature decreases as the radius of the circle increases
Globe
You might have seen a globe. A globe is a model of the Earth. Is the globe identical to the real Earth? If not, find out as many differences as you can! Three differences are given in this table.
The Earth
The Globe
Solid
Hollow (usually)
Huge mass (5.972 x 1024 kg)
Light
Strong gravitational force
Negligible gravitational force
Can you think of other differences? (Click on the icon to write)
If the Earth is spherical, where do we live? We live all over on the surface of the Earth. Let us see how people stand on the Earth.
Glossary
You may have heard that shape of the Earth is spherical. But are you sure that it is really spherical? The land beneath us looks quite flat. Think of at least one piece of evidence to show that the Earth is spherical. One such evidence, which was proposed more than 2300 years ago, is given in one of the later lessons. Of course, now we have photographs of the Earth taken from space, but we could fly the space-crafts only after knowing that the Earth is round!
If the Earth is spherical, why does it appear flat to us?
That is because it is too big! You may notice that a piece of a round flask looks almost flat.
Something similar thing is happening here. In Figure 1, as the circle becomes bigger, its rim appears more flat. Doesn't a portion of a football appear more flat than a portion of a ping- pong ball that is of the same size? You may know the rule in geometry that the curvature reduces as the radius increases.
Figure 1: Curvature decreases as the radius of the circle increases
Globe
You might have seen a globe. A globe is a model of the Earth. Is the globe identical to the real Earth? If not, find out as many differences as you can!
Three differences are given in this table.
The Earth
The Globe
Solid
Hollow (usually)
Huge mass (5.972 x 1024 kg)
Light
Strong gravitational force
Negligible gravitational force
Can you think of other differences?
(Click on the icon to write)
If the Earth is spherical, where do we live? We live all over on the surface of the Earth. Let us see how people stand on the Earth.