1. Hydrogen Fusion: Our Sun, like most stars, generates energy by fusing hydrogen atoms into helium in its core. This process releases immense amounts of energy, which creates outward pressure that balances the inward pull of gravity.
2. Hydrogen Depletion: Over billions of years, the Sun's core gradually runs out of hydrogen. As the hydrogen fuel dwindles, the rate of fusion slows down, reducing the outward pressure.
3. Gravitational Collapse: Without the outward pressure from fusion, gravity starts to dominate. The core of the Sun begins to contract, becoming denser and hotter.
4. Helium Fusion: As the core contracts, the temperature and pressure increase enough to initiate helium fusion. This process is much less efficient than hydrogen fusion, meaning the star releases less energy.
5. Red Giant Phase: The star expands dramatically, becoming a red giant. The outer layers cool down, giving the star its reddish appearance.
6. Helium Depletion: Eventually, the helium in the core is also depleted. The star continues to contract and heat up, eventually reaching a point where it can't sustain any further fusion.
7. White Dwarf Formation: The core of the Sun will eventually stabilize as a white dwarf, a very dense, hot object that slowly cools over trillions of years. The outer layers of the star will be expelled into space, forming a planetary nebula.
Important Note: Our Sun is not massive enough to undergo a supernova explosion, which occurs in stars much larger than the Sun. The Sun's ultimate fate is to become a white dwarf.
