What is the ultimate fate of our sun?

Asked by: Saurabh Gedam

Answer

The Sun shines by converting hydrogen in its core into helium, and in the process loses mass that is converted to energy via Einstein's E=mc². It has been doing this for about 4.5 billion years, and is expected to do so for 5 billion more years. After that time, its hydrogen fuel will be depleted. With its internal energy source shut down, gravity will cause the core to collapse. That collapse will generate enough heat to expand its outer layers, turning our Sun into a red giant that will expand beyond the Earth's orbit. (So don't make any plans for the year 5,000,002,000.)

The collapsed core will become a white dwarf, composed of degenerate matter supported by the inability of two electrons to occupy the same space. A star more massive than our Sun eventually becomes a neutron star via a similar process. The most massive stars collapse to form black holes.
Answered by: Paul Walorski, B.A. Physics, Part-time Physics Instructor