12 Days of Geek | Day 11 | The fate of the sun Dec 16, 2015 by Julian Fields in 12 Days of Geek Q. What is the earth’s sun expected to become at the end of its life? One day our Sun will die. At 4.6 billion years old, it’s currently about halfway through its life. While too small to go out in a giant supernova bang, 5 billion years from now, as it runs out of hydrogen fuel, the Sun will expand as a red giant, engulfing the orbits of nearby Mercury, Venus and Earth.At this point the Sun’s outer layers will be so unstable that they will fly off into space and form planetary nebula. What remains of the Sun will begin to compact and slowly cool as a white dwarf roughly the size of Earth.