In roughly 5 billion years, the Sun will run out of energy and drastically alter the solar system. Oceans will be baked dry. Entire planets will be consumed. And long-icy worlds will finally enjoy their day in the Sun.
Our star is powered by nuclear fusion, and it turns hydrogen into helium in a process that converts mass into energy. Once the fuel supply is gone, the Sun will start growing dramatically. Its outer layers will expand until they engulf much of the solar system, as it becomes what astronomers call a red giant.