The Sun will go out sometime. The scientists estimate that it will have a future existence of about 4.5 billion years. The period seems long, but it is by the human standards. In fact, it is not a long time for the cosmic period. The scientists believe that the problem will arise much earlier and it is associated with the old Sun itself. Hydrogen synthesis continues inside the star, as a result of that reaction helium accumulates in the core.
In order to constantly maintain the temperature of its thermonuclear reactions, the Sun has to constantly increase it, and it leads to an increase in the temperature of the core. It means that over time, the Sun will get brighter.
For example, the dinosaurs that lived millions of years ago saw the Sun dimmer than we do that. And in just a few hundred million years, the Sun will be so bright that the Earth will become extremely hot for safe living on it. The planet's atmosphere will disappear, the oceans will evaporate, for a while the Earth will be like the Venus that is surrounded by an atmosphere of carbon dioxide. Then the situation will worsen. The final stages of hydrogen synthesis will lead to the fact that the Sun will, as it were, swell, increase in size and turn red.
The growing giant will absorb the Mercury and then the Venus. If the stretched atmosphere of the Sun reaches the Earth, then our planet will dissolve in it, in less than a day. But there is an option when at a certain moment the expansion of the Sun will stop.
That option will not bring anything good either. The star will emit extreme energies that will become intense to vaporize the rocks. And it will leave only the dense core of the Earth and nothing more after that. Other planets from the increased radiation of the Sun will also not get anything good. The Saturn's rings, which are composed of pure water ice, will melt completely. Many satellites, including Enceladus, Europa, will also lose their ice shells.
The planets will be hit by increasing radiation. It will rob the planets of their atmosphere, and then, as the Sun grows in size, its impact will find a way to travel through the funnels of gravity. Feeding on its energy, the planets will begin to increase in their volumes.
At the final stage of the existence of the Sun, it will begin to swell and contract, creating pulsations over millions of years. The Sun will push all planets in different directions, creating a death embrace or pushing them completely out of the Solar System.