The Fate of the Stars
All scenes › Chapter 4 A Sun-like star: white dwarf
Red giant
The Sun-like star swells up red
View in 3DA swollen red Sun
The lightest star, the Sun-like one, lives much longer. Only after about 10 billion years does the hydrogen in its center run out, and it swells into a red giant. It becomes about 200 times wider than before, reaching close to Earth’s orbit. Our own Sun, now about 4.6 billion years old, will start to swell like this in about 5 billion years.
Why?When the hydrogen in the center runs out, the center shrinks and heats up, and hydrogen just outside it starts joining again, pushing the surface outward. Mercury and Venus are expected to be swallowed.
Learn moreIt is not yet certain whether Earth will be swallowed. As the Sun loses gas and gets lighter, the planets drift outward. Either way, Earth will be far too hot for life by then.
- When
- About 10 billion years old
- Star we are watching
- Sun-like star → red giant
- Size · state
- About 200 times wider than before
Read more
Wikipedia: Red giant · Wikipedia: Sun
More in the series
Lifetimes and sizes are typical values from models of how stars change (approximate). The black hole horizon size and the teaspoon masses are calculated with official constants. Sizes, distances and speeds in the 3D view are a rough sketch.