A star is a massive, self-luminous celestial body consisting of a mass of gas held together by its own gravity in which the energy is generated by nuclear fusion reactions. The nearest star to Earth is the SUN, which is the source of most of the energy on Earth. Other stars are visible from Earth during the night, when they are not obscured by atmospheric phenomena, appearing as a multitude of fixed luminous points because of their immense distance.
A nebula is an interstellar cloud of dust and gases where stars are born. All stars began their lives as a nebula. In these regions the formations of gas, dust, and other materials “clump” together to form larger masses, which attract further matter, and eventually will become massive enough to form stars. As a star dies it returns its material to the cosmos as another nebula. It is through this release of matter that the universe is provided with all the elements heavier than hydrogen and helium. This includes all the material that forms the Earth and everything on it, including humans. The oxygen we breathe was formed in the hearts of giant stars and the iron in our bloodstream was formed in the final days of a massive star’s existence before it ripped itself to pieces as a supernova.
It is from this that we get the saying that we are all made of stardust….
