The sun is a fusion reactor that is running out of fuel. The Sun has a lifespan of about 5 billion years. This does not mean that we have time for another 500 billion years. A recently published study estimates that our atmosphere may lose oxygen in about 1 billion years.
During the last days of the sun, the magnitude of the sun rises, which warms the earth’s atmosphere. Thus this heat is absorbed and carbon dioxide decomposes. When carbon dioxide levels fall, photosynthesis of plants and phytoplankton becomes extinct. This reduces the amount of oxygen. At the same time, increasing methane levels can accelerate the decline of oxygen-breathing organisms.
Eventually only small anaerobic organisms will remain for a few more days and eventually the sun will swallow up the earth or disintegrate it.
We know that these events will occur, but this study was done using computer simulation to tell the exact time scale in which it is likely to occur.
Researchers say the study not only highlights the destruction of Earth, but will also help our search for other habitable planets. The message when searching for such solar systems is to look for worlds that are not similar to Earth but have a slightly more initial stage / window of opportunity.