Answer:
Newton contributed to astronomy by <u><em>developing theories of gravity and motion.</em></u>
Explanation:
Newton reflected on the fact that bodies weighed on Earth and that the stars revolved around other stars. He imagined that there was a universal force that caused bodies to attract each other. Newton called it "Universal Gravitation Force" or "Gravity."
Then, the force of gravity is the physical force exerted by the mass of a planet on the objects that are within its gravitational field. In other words, this law establishes that bodies, by simply having mass, experience a force of attraction to other bodies with mass.
Objects are attracted according to their mass and the distance between their centers: if the distance increases, the force decreases, and if the mass increases, the Universal Gravitation Force is more intense:

where G is the universal gravitation constant, whose value is
This expression indicates that the gravitational force that a point mass M exerts on another point mass m that is at a distance r from the previous one is directly proportional to the product of the masses and inversely proportional to the square of the distances that separates them.