In the center of most stars, hydrogen fuses together to form helium. Fusion in stars releases so much heat that the process alone keeps their mass from collapsing in on itself due to [[gravity]]. It is the reason that stars are so stable as well. If the core of a star starts to collapse, more fusion reactions occur and it expands again from the heat. If the core expands too far, less fusion reactions occur and it collapses back down. | In the center of most stars, hydrogen fuses together to form helium. Fusion in stars releases so much heat that the process alone keeps their mass from collapsing in on itself due to [[gravity]]. It is the reason that stars are so stable as well. If the core of a star starts to collapse, more fusion reactions occur and it expands again from the heat. If the core expands too far, less fusion reactions occur and it collapses back down. |