The Sun

Facts

The Sun is a middle aged, yellow dwarf star.
Over one million Earths could fit inside the Sun.
It is almost three quarters hydrogen and nearly one quarter helium with a small amount of heavier elements.
Nuclear fusion in the Sun generates heat and light, and creates the heavier elements including oxygen, carbon, silicon, neon and iron.
The Sun will eventually run out of fuel a long time in the future (in about 5 billion years), it will grow into a red giant and it will engulf some of the inner planets, possibly including the Earth.