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 …showed first 75 words of 1115 total…

…showed last 75 words of 1115 total…apart causing a massive, bright, short-lived explosion called a supernova. If the remaining core's mass is between 1 1/2 to 3 solar-masses, it will collapse into a small, dense neutron star. If the star's remaining mass is greater than three solar-masses, the star contracts to become a black hole. Works Cited: Seeds, Michael A.. Horizons: Exploring the Universe. 7th ed. Brooks/Cole, 2002 Lattanzio, Stephen, et al. Telecourse Student Guide for UNIVERSE The Infinite Frontier. 4th ed. Brooks/Cole, 2002