Planet
The planets are made of elements that are very different from the Sun (which is mostly hydrogen). The Sun is mostly made up of hydrogen, with some helium. Its energy comes from converting hydrogen to helium. In contrast, the planets are mostly made up of larger atoms and molecules which could not have come from the Sun. The materials of planets must have come from another source or sources. Those sources were atoms made in earlier supernovae explosions near the Sun's path as it moved through its part of the Milky Way. The material captured by the Sun's gravity formed the planets. The same thing happened in other planetary systems in the galaxy.