The force of gravity on a person or object at the surface of a planet is known as?

Gravity always produces a pair of forces ... two of them.

The forces are opposite.

One force pulls 'A' toward 'B'.

The other force pulls 'B' toward 'A'.

For this question, let's say Astronaut Bob is standing on Mars.

There are two forces of gravity between the Astronaut and the planet.

One force pulls Bob toward Mars.

The other force pulls Mars toward Bob.

The force that pulls Bob toward Mars is what we call his "weight".

The other force ... the one that pulls Mars toward Bob ... is

the force that nobody ever talks about, but it's there.

The force that attracts you toward the Earth is

your "weight" on Earth.

The force that attracts the Earth toward you is

the Earth's weight on you.

The two forces are equal!