What is the importance of universal law of gravitation?

Universal law of gravitation states that there is a force acting between any two objects. It is an attracting force that acts between each object of the universe. This force is said to be a gravitational force.

The gravitational force between any two objects is directly proportional to the masses of the objects and inversely proportional to the square of the distance between the objects.

If there are two objects of masses $m_1$ and $m_2$. And the distance between the two objects is $r$

Then,

So, $F\propto m_1$           .......... $(i)$

$F\propto m_2$                 .......... $(ii)$ 

$F\propto \frac{1}{r^2}$     ........ $(iii)$

From $(i)$, $(ii)$ and $(iii)$

$F\propto \frac{m_1m_2}{r^2}$

Or $F=G\frac{m_1m_2}{r^2}$

Here $G$ is a universal constant.

(i).  The universal law of gravitation is used to determine the masses of the sun, the earth, and the moon accurately. 

(ii). The universal law of gravitation is also used in discovering new stars and planets in the universe.