* Formation: Billions of years ago, the moon formed from a giant collision between Earth and a Mars-sized object. The debris from this collision coalesced under its own gravity.

* Gravity's Pull: Gravity pulls equally on all sides of a massive object like the moon. This even pull creates a spherical shape, as it pulls all the material towards the center.

* Equilibrium: The round shape is the most stable and balanced form for a large object like the moon. Any other shape would have uneven forces acting on it, causing it to shift and eventually become more spherical.

Think of a drop of water. It forms a sphere because of surface tension, which acts similarly to gravity. In the case of the moon, gravity is the dominant force, pulling everything into a perfectly round shape.