when will the sun explode?

The Sun will not explode like a supernova—it's not massive enough (only about 1 solar mass). Instead, it follows standard stellar evolution for G-type stars:

Timeline

• Now: Midway through its ~10-billion-year main sequence life (age ~4.6 billion years).
• In ~5 billion years: Hydrogen fuel depletes; core contracts, outer layers expand into a red giant, potentially engulfing Mercury, Venus, and Earth.
• ~7-8 billion years from now: Sheds outer envelope in planetary nebulae, leaving a cooling white dwarf core (Earth-sized, no fusion).

This is based on well-established models like those from the Hertzsprung-Russell diagram and simulations (e.g., MESA stellar evolution code). Human timescales are irrelevant—far beyond civilization's lifespan.