The successful colonization of the entire solar system could potentially extend the survival of humanity for a significantly longer period compared to being confined to Earth. However, it's important to note that even with colonization efforts throughout the solar system, the ultimate fate of humanity would still be tied to the lifespan of the sun.
If we consider the moons of the outer planets, such as Europa (moon of Jupiter), Titan (moon of Saturn), or Enceladus (moon of Saturn), these locations could provide potential habitats for humans. They have diverse environments, with the possibility of subsurface oceans and potential resources. However, they would still rely on a stable energy source for survival, and the availability of such energy would decrease significantly as the sun ages.
As the sun goes through its natural life cycle, it will eventually exhaust its hydrogen fuel and start to expand into a red giant, engulfing the inner planets, including Earth. This phase is expected to occur in about 5 billion years from now. The outer planets, their moons, and objects in the Kuiper Belt and Oort Cloud would still be at a considerable distance from the sun, and they might avoid direct destruction during this phase.
However, the long-term survival of colonies in these regions would face challenges. The sun's expansion would lead to a significant decrease in solar energy reaching these distant regions, making it increasingly difficult to sustain life. Additionally, the outer planets and their moons are not capable of producing their own energy through nuclear fusion like the sun, so they would be dependent on imported energy sources or finding alternative means of generating power.
Furthermore, over an even longer timescale, the sun would eventually shed its outer layers, forming a planetary nebula, leaving behind a dense, hot core known as a white dwarf. The intense radiation and gravitational interactions during this phase could still pose a threat to the survival of colonies in the outer regions of the solar system.
In summary, while colonizing the entire solar system could prolong the survival of humanity, it would not provide a permanent solution. Eventually, the aging sun and its changing conditions would make it increasingly challenging to sustain life, even in the outer regions of the solar system. To ensure our long-term survival, humans would need to consider interstellar travel or other means of expanding beyond the limitations of our solar system.