This is a review chapter. Important concepts treated include the nuclear model of the atom, types of nuclear reactions, wave properties, the electromagnetic spectrum of light, Doppler shifts, blackbody radiation, and galaxy classifications. Read through this material to obtain background for later chapters.
Blackbody radiation is a very specific type of spectrum that corresponds to photons in equilibrium.
This radiation is completely characterized by one parameter, the temperature of the emitter. The cosmic background radiation is an example of blackbody radiation, where the emitter is the universe itself. Nuclear Fusion is the phrase for nuclear reactions that combine light elements into heavier. Stars are powered by fusion. This process also explains how the elements in the universe are built up from the original protons and neutrons in the process of nucleosynthesis .