What do we mean when we say that the Sun is in gravitational equilibrium?
1. The Sun maintains a steady temperature.
2. The hydrogen gas in the Sun is balanced so that it never rises upward or falls downward.
3. There is a balance within the Sun between the outward push of pressure and the inward pull of gravity.
4. The Sun always has the same amount of mass, creating the same gravitational force.
5. This is another way of stating that the Sun generates energy by nuclear fusion.