Final answer:
Gravitational equilibrium is the state where the outward pressure, including thermal and radiation pressure, balances the force of gravity within a star, maintaining its stability.
Step-by-step explanation:
The two forces that are balanced in gravitational equilibrium are outward pressure, which includes thermal pressure from nuclear fusion, as well as radiation pressure, and gravity, which is the force that tends to pull matter inward. When a star is in gravitational equilibrium, these two forces are equal and opposite, meaning that the inward pull of gravity is exactly counteracted by the outward pressure created by the high temperatures and radiation within the star's core. This balance is crucial for a star's stability and is what keeps it from collapsing or expanding uncontrollably.