About this episode
The episode discusses the future of the Sun as it transitions to a white dwarf due to the cessation of nuclear fusion.
The Sun faces a “degenerate” future. That’s not a value judgment – it’s physics. When the Sun can no longer produce nuclear reactions, its core will collapse. How far it collapses is limited by a type of pressure exerted by its atoms – degeneracy pressure. Today, the Sun is “fusing” atoms of hydrogen to make helium. When the hydrogen is gone, it’ll fuse the helium to make carbon and oxygen. But the Sun isn’t massive enough to extend that process, so its nuclear furnace will be extinguished. Fusion releases energy, which balances the pull of gravity. That keeps the Sun puffed up. Right now, it’s big enough to hold a million Earths. When fusion stops, gravity will win out. The core will shrink to the size of Earth itself. But it’ll still be about half as heavy as the present-day Sun. So a chunk the size of a sugar cube would weigh a ton. The dead core won’t shrink beyond that. That’s because the electrons in the core will exert their own pressure – degeneracy pressure. They can be squeezed only so much before they run out of “elbow room” and halt the collapse. That will leave a…
People in this episode
Host: Billy Henry
Topics covered
- Sun
- degeneracy pressure
- nuclear fusion
- white dwarf
- stellar evolution
Keywords
- Sun
- degeneracy pressure
- nuclear fusion
- white dwarf
- stellar evolution
- gravity
- helium
Mentioned in this episode
Places: Sirius, Earth, galaxy
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