However, as the Sun reaches this late stage in its stellar evolution, it loses a tremendous amount of mass through powerful stellar winds. As it grows, it loses mass, causing the planets to spiral outwards. So the question is, will the expanding Sun overtake the planets spiraling outwards, or will Earth (and maybe even Venus) escape its grasp.
|Red Giant Diagram|
K.-P Schroder and Robert Cannon Smith are two researchers trying to get to the bottom of this question. They’ve run the calculations with the most current models of stellar evolution, and published a research paper entitled, Distant Future of the Sun and Earth Revisted.
According to Schroder and Smith, when the Sun becomes a red giant star 7.59 billion years, it will start to lose mass quickly. By the time it reaches its largest radius, 256 times its current size, it will be down to only 67% of its current mass.
|Artist's impression of the surface of the Earth with Red Giant Sun and Moon in background|
But the habitable zone will be gone much sooner. Astronomers estimate that will expand past the Earth’s orbit in just a billion years. The heating Sun will evaporate the Earth’s oceans away, and then solar radiation will blast away the hydrogen from the water. The Earth will never have oceans again. It will eventually become molten again.
One interesting side benefit for the Solar System. Even though the Earth, at a mere 1.5 astronomical units, will no longer be within the Sun’s habitable zone, much of the Solar System will be. The new habitable zone will stretch from 49.4 AU to 71.4 AU, well into the Kuiper Belt. The formerly icy worlds will melt, and liquid water will be present beyond the orbit of Pluto. Perhaps Eris will be the new homeworld...
|Expect the lakes of Titan to melt and potentially harbour life|