Both earth and an apple (smaller objects) accelerate toward each other due to the force of gravitation but an apple appears a lot to the earth due to its greater acceleration as compared to the earth toward an apple, which is so minuscule to be distinguished.

Since the difference in masses is mammoth therefore it seems that not only the earth is stationary as compared to an apple but also the reduction in on-center distance "d" occurs due to falling of an apple **ONLY** (in its acceleration mode), but verily, both masses are changing their positions and hence on-center distance decreases due to the falling of both masses in their higher derivatives of motion (complex motion) before they strike each other.

This can easily be observed if the difference in masses is not so huge or if we consider the following two identical spherical masses (from point to celestial), which are separated by on-center distance “d”.

First Mass = M_{1}, Second Mass = M_{2}, M_{1} = M_{2} = Identical, Centre-to-Centre distance b/w M_{1} and M_{2} = d, d_{1} = d_{2}, d_{1} + d_{2} = d, Gravitational acceleration of M_{1} = g_{1}, Gravitational acceleration of M_{2} = g_{2}, g_{1}=g_{2} and “c” be the mid point of “d".

Although, both M_{1} and M_{2} strike each other at “c” as per universal law of gravitation but since none of the M_{1} or M_{2} is stationary at “c” therefore neither M1 covers a distance d1 with g_{1}=g_{2} nor M_{2} covers a distance d_{2} with g_{1}=g_{2} on their road to “c”. Acceleration g_{1}=g_{2} is only possible if either M_{1} or M_{2} is stationary at “c”.

The earliest imaginable motions of M_{1} and M_{2} towards “c” might be due to the generation of g_{1} & g_{2} and the reduction in d (reduction in "d_{1}" and "d_{2}" equally on both sides of “c”) as well but after that both M_{1} and M_{2} start moving toward “c” at higher types of motion (such as gravitational jerk, jounce, crackle, pop, lock, drop etcetera or complex motion) as d_{1} and d_{2} decreases equally on both sides due to the change in positions of both M_{1} and M_{2} while on their ways to "c".

Both M_{1} and M_{2} move at much faster rate due to the formation of the complex motion instead of simply with accelerations before they hit each other at “c”. The actual striking time of M_{1} and M_{2} at "c" is much less than estimated by g_{1} and g_{2} combined.

So is F=GMm/d^_{2} well formulated?

**Addendum: As gravity is universal therefore physical objects orbits other physical objects and hence causes the motions of planets, stars, and galaxies in the universe. **