The Sun is a main sequence star, which means that it is currently fusing hydrogen into helium in its core. This process releases energy, which causes the Sun to shine and emit heat. As the Sun continues to fuse hydrogen, it will gradually build up a core of helium. When the core of the Sun becomes large enough, it will no longer be able to support the outer layers of the Sun. These outer layers will then expand and cool, forming a red giant star.

The red giant star will continue to expand until it reaches a point where it is unstable and begins to shed its outer layers. These outer layers will form a planetary nebula, which is a glowing shell of gas and dust. The core of the red giant star will then collapse to form a white dwarf, which is a dense, hot remnant of a star.

The Sun is currently about 4.6 billion years old, and it is expected to become a red giant star in about 5 billion years. It will then take another few thousand years for the Sun to shed its outer layers and form a planetary nebula.