Why don't stars just collapse to Black Holes right away?

Recall, the center of the Sun, a typical star is


        T = 15 Million Kelvin Degree, and the Density = 150 x Water!

        Pressure ~ (is proportional to) Temperature x Density




Why is the Sun HOT and DENSE at its center?













This internal PRESSURE pushes outward against the Gravitational PRESSURE







THERMONUCLEAR FUSION


THERMO = heat (in this case EXTREME temperatures)


NUCLEAR = having to do with the nuclei of atoms


FUSION = the fusing of two things to become one.


At the center of OUR SUN, 4 Hydrogen nuclei are fused to become 1 Helium nucleus. The single Helium nucleus weighs less (smaller mass) than the 4 Hydrogen nuclei.

Where does the Mass go???

The excess mass is converted to ENERGY using Einstein's Famous equation:

E = mc²