As the sun nears the end of its Red Giant phase, most of its outer layers (which contain the lightest elements) will be vented off into space. This forms a planetary nebula. The lighter elements from the sun are forcefully vented into space, but this should not be confused with a supernova that happens to more massive stars. This is the shortest phase of the sun's life cycle. The result is that the sun loses mass at a high rate and becomes cooler in temperature, but very bright. Eventually, all that will be left of our star is its dense core.