(Here, ``h'' refers to Planck's Constant)
We will find that astronomical sources that put out a lot of high energy
light, such as Gamma-Rays, X-rays or Ultraviolet light, are usually very
HOT , while sources emitting at long wavelengths,
infrared and radio, are usually very COLD.
We will study two main physical processes which create
LIGHT in the Universe. Understanding HOW these processes
occur is vitally important to our interpretation of astronomical sources.
1) BLACK BODY RADIATION
Another very important point about light is the ENERGY it carries. We
know from our own experience that Gamma Rays and X-Rays are very dangerous.
They have very HIGH frequencies, and very SHORT wavelengths. The Energy
associated with a particular photons depends on its wavelength (or frequency):
BUT How is light CREATED?
2) ATOMIC & MOLECULAR TRANSITIONS