In 5 Billion Years, Our Sun Will Become This

In about five billion years, our Sun will die, and what it leaves behind will fit inside Earth.

The Sun is over a million times Earth's volume. Yet its final form, a white dwarf, will be Earth-sized while still holding half the Sun's mass.

First the Sun will swell. Running low on hydrogen, it balloons into a red giant and swallows Mercury, Venus, and probably Earth. Then it blows its outer layers off as a glowing shell called a planetary nebula. What remains is the bare core: a white dwarf the size of a planet, with no fuel left. Then it cools for billions of years, fading from white to orange to red. The Sun will shine ten billion years, then spend far longer as a cooling ember in the dark.

Every glowing shell in a planetary nebula is a star caught in the act of dying. One day our Sun will paint one, then quietly go out.

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