What will cause the death of the solar system?

Answer 1

When the sun expands into a red giant it will swallow Mercury and Venus and extinguish life on earth. Actually, earth will be uninhabitable more than a billion years before then.

Then the sun will collapse into a hot, bright white dwarf, and burn for billions of years to come. The mass ejection in the red giant stage will cause the remaining planetary orbits to expand slightly, but none of the outer planets will be lost. Eventually the sun will burn out altogether, perhaps ten billion years hence.

Trillions of years from now, during the black hole era most of the matter in the universe will be inside of black holes. During this time it's conceivable that the solar system will had been swallowed by such a black hole. The expectation is that the sun will have spiraled into the black hole at the center of the galaxy, and long, long after that the Andromeda and Milky Way black holes will coalesce.

Answer 2

The death of the solar system will likely be caused by the sun running out of fuel and expanding into a red giant, engulfing the inner planets, including Earth. Eventually, the sun will shed its outer layers and become a white dwarf, while the remaining planets drift off into space or are pulled into different orbits by gravitational interactions.