Hydrostatic equilibrium

Hydrostatic equilibrium is the balance within a star or planet between the outward pressure from the hot, dense material inside and the inward pull of gravity pulling everything toward the center. This balance keeps the object stable; if pressure were too high, it would expand, and if gravity were stronger, it would contract. Essentially, the system is in a steady state where these opposing forces cancel each other out, maintaining the object's shape and size over time.