Final answer:
Gravity is the dominant force between astronomical objects due to its infinite range. The other three basic forces - electromagnetic force, weak nuclear force, and strong nuclear force - are less significant over very large distances.
Step-by-step explanation:
The dominant force between astronomical objects is gravity. Gravity has an infinite range and is the force that determines the motions of moons, planets, stars, and galaxies on a very large scale.
The other three basic forces - electromagnetic force, weak nuclear force, and strong nuclear force - are less significant over these very large distances because they either have short ranges or are much weaker than gravity.