Astronomers say that the Sun only has 5 billion years of life left, after which it will expand into a red giant star, engulfing Mercury, Venus, and possibly Earth. However, for us humans, we don't have that much time. 

Before the Sun becomes a red giant, its brightness will increase due to intensified nuclear fusion reactions, with a 1% increase every 100 million years. After 1 billion years, the Sun's brightness will be 10% higher than it is now. This additional heat will have a significant impact on the climate-sensitive life on Earth. Despite our efforts in carbon reduction, a slight increase in solar brightness could push global temperatures beyond our control. 

Scientists agree that in 1 billion years, Earth will be ejected from the habitable zone of the solar system and become like Venus. As the Sun's brightness increases, polar ice caps will melt, oceans will warm, and water will evaporate into the atmosphere, triggering an enhanced greenhouse effect. This scenario might lead to the idea of the "Wandering Earth" plan, pushing Earth to a new habitable zone in the solar system, like the orbit of Mars. 

Although it seems crazy, we have enough time to develop the necessary technology within the next 500 million years and attach engines to Earth, ensuring it stays within the habitable zone. However, the long-term sustainability of human civilization is uncertain, and the Wandering Earth plan itself has flaws. Instead, we could build space cities that can accommodate all of humanity, exploiting abundant resources in space and becoming a spacefaring civilization capable of traveling to other star systems.