There have been two scenarios developed and discussed for the future evolution of the sun and its probable effect upon life on the planet earth. The first is that the sun becomes a red giant, increasing in size 400 times thereby almost touching the Earth and reducing this planet to a molten rock, and the second, that the sun is affected by solar winds and reduced in size by 40% thereby loosing its gravitational hold upon Earth causing this planet to spiral outward from its present gravitation path.
Taking into account the sun's present composition, mass and stage of evolution, scientists have concluded that Earth has a minimum of 1.1 billion years before it becomes uninhabitable due to increased heat from the sun. The consensus of opinion is that the sun will evolve into a red giant which will make life on Earth impossible. The giant red phase would swallow up the planets Mercury, Venus and possibly Earth. A reduction in the sun's size through the effects of solar winds would cause a shift in the Earth's gravitational path around the sun from its present 92 million miles to an estimated 172 million miles. However, scientists are not in agreement over the means by which the sun looses mass.