Analysis:
Swallowed by a red giant that evolved from the sun.
Stars have a certain life cycle: they form stars-main sequence stars-red giant stars-white dwarfs, neutron stars (pulsars) and black holes.
Among them, the main sequence star is a stable star, the energy that makes it glow and heat is nuclear energy, and the sun is a main sequence star. Red giant is a necessary stage for most stars, and the sun will become a red giant in 5 billion years. Both white dwarfs and neutron stars are in the late stage of star evolution, in which white dwarfs evolved from stars with smaller mass and neutron stars evolved from stars with larger mass. More massive stars will evolve into black holes.
The forming star relies on gravitational potential energy to emit light and heat; Main sequence stars rely on hydrogen nuclear fusion to emit light and heat, red giant stars rely on helium nuclear fusion to emit light and heat, and white dwarfs and neutron stars rely on cooling to emit light.
Supernova explosion is an explosion with huge energy when massive stars evolve to form neutron stars or black holes in the later stage. Supernova explosion is the direct driving force for the birth of some stars and the reason for the formation of various elements.
After billions of years, the sun will continue to expand from the red giant and the earth will be swallowed up. Then the sun shrinks into a white dwarf. When the sun evolves into the final black hole stage, all the substances in the solar system, including the sun itself, will be swallowed up by the black hole. So the earth civilization will return to zero.