And in the sequel (to the Apple Story)

As the apple story told by Newton, if matter draws matter, it must be in proportion of its quantity. Therefore, the apple draws the earth, as well as the earth draws the apple. 

Let's elaborate on what the apple story tells us. The quantity of matter, to which the power to draw other matter is proportional is known as mass. And, the power to draw matter on account of its mass is known as gravity (gravitational force). More the mass, more is the gravity. The apples from all around the earth fall towards the centre of the earth. And, while every apple is also pulling the earth towards itself, the resultant movement is these apples falling towards the centre of the earth. This means that the earth is having a huge mass. 

Now, are you ready to get a taste of something of a larger scale? If you are ready to use the knowledge gained from the story, ponder upon the following questions. 

What do you think must be happening with something bigger than and much massive as compared to an apple, but less massive than the earth? For example, the moon?
Why doesn't the moon fall towards the centre of the earth, just like an apple?

https://www.needpix.com/photo/download/1192241/planet-moon-earth-companion-sky-celestial-body-astronomy-solar-system-space-star

Well, in fact, the moon that is 81 times less massive (lighter) than the earth is falling towards the centre of the earth all the time. But, it hasn't hit the ground like an apple yet. The reason is, the moon is having certain motion, known as a tangential motion (linear - trying to follow a straight line). The moon has some velocity (in the direction perpendicular to the line joining it to the centre of the earth) with which it moves in the space. At the same time, the earth pulls it towards its centre. Both the things happen simultaneously making the moon orbit the earth, at the same time not hitting the earth by keeping itself in motion. 

AlvaroLopez12 / CC BY-SA (https://creativecommons.org/licenses/by-sa/4.0)

To make it simpler, let us consider an example: you holding one end of a string with a ball tied to its other end. Now, if you start twirling the ball around the end fixed in your hand, you will notice the ball is making an orbit around this fixed point. If accidentally, you happen to loose the control over the end you've been holding, or the string is cut during this motion, the ball will get thrown away in a straight line tangential to the orbit. Here, the string acts as the power to draw or gravitational pull of the earth (you) on the moon (ball).

The moon is the closest celestial example to us. We all are hold to the earth by gravity. We can walk, run, jump, have all the fun we do due to gravity. Imagine all the chaos that would have been created if we existed without the overwhelming gravity of the earth.

Can you think of any funny incidents those could happen with the world we live in, in the absence of the earth's gravity? If yes, feel free to share the fun with us by putting those ideas in comments.

✍ Sonal Thorve