The Birth and Death of Stars

Between the stars, there is a region, called the interstellar medium, which contains huge clouds of gases and solid particles. It is comprised of about 75% hydrogen, 25% helium, and traces of carbon, nitrogen and other elements. The clouds, called nebulae, are cool and relatively dense and are shaped by currents of hot, low-density gases. It is in these nebulae, that certain processes come together to form stars.
Stars form when a shock wave passes through a nebula, compressing the clouds and causing the gases and dust there to clump together. …