The Life Cycle of Stars

Stars initially form from clouds of DUST AND GAS. The force of gravity makes the gas and dust spiral in together to form a PROTOSTAR.

Gravitational evergy is converted into heat energy, so the temperature rises. When the temperature gets high enough, hydrogen nuclei undergo nuclear fusion ti form heluim nuclei and give out massive amounts of heat and light A star is born. Smaller masses of gas and dust may also pull together to make planets that orbit the star.

The star immediately enters a long stable period, where the heat created by the nuclear fusion provides an outward pressure to balance the force of gravity pulling everything inwards. The star maintains its energy output for millions of years due to the massive amounts of hydrogen it consumes. In this stable period it's called a MAIN SEQUENCE STAR ad it last several billion years.

Eventually the hydrogen begins to run out. Heavier elements are made by nuclear fusion of helium. The star then swells into a RED GIANT, if it's a small star, or a RED SUPER GIANT if its a big…