1. Stellar Nebula: This is the starting point. A cloud of gas and dust, mostly hydrogen and helium, collapses under its own gravity.
2. Protostar: As the nebula collapses, it heats up and spins faster. The core reaches a temperature high enough for nuclear fusion to begin.
3. Main Sequence: This is the longest stage of a star's life. The star fuses hydrogen into helium in its core, generating energy and creating outward pressure that balances the inward force of gravity.
4. Red Giant: As the hydrogen in the core runs out, the core contracts and heats up. This causes the outer layers of the star to expand and cool, making it appear redder and larger.
5. Helium Fusion: In some stars, the core becomes hot enough to fuse helium into heavier elements, like carbon and oxygen. This stage is relatively short.
6. Planetary Nebula: As the star's outer layers are ejected into space, they form a glowing shell of gas and dust, known as a planetary nebula.
7. White Dwarf: What's left behind is a dense, hot core of carbon and oxygen, called a white dwarf. This stage is the final stage for most stars, including our Sun.
Important Note: This is a simplification. More massive stars have more complex life cycles, potentially leading to supernovae, neutron stars, or black holes. The exact path a star takes depends on its initial mass.
