How was the spectral classification system arrived at? Relate its construction to the Calmer series and explain how a star’s spectral class can give us clues to its temperature, motion, and chemical composition.

Michael Seeds, the author of your textbook, has been quoted saying that, “To an astronomer, nothing is so precious as starlight”.** Today we recognize that this starlight is electromagnetic radiation. List the following:
Each part of this radiation used by an astronomer. B. What instrument (telescope, etc.) works best with each type of radiation.
C. What celestial objects we study and what we learn about them from the radiation they emit.
D. What special instruments work in conjunction with telescopes to advance our studies of “starlight.”
**quote from Seeds, M. A. (2007). Foundations of astronomy. Belmont, CA: Thomson Brooks/Cole.

2. The ultimate key to our understanding the universe is our knowledge of the atom.
A. Illustrate with an example the difference between an atom and an ion.
B. Describe two ways an atom can be excited.
C. Why should photons emitted by a hotter material have an average shorter wavelength?
D. Atoms produce spectra. Distinguish between a continuous, a bright-line, and an absorption spectrum by describing how each is formed.

3. How was the spectral classification system arrived at? Relate its construction to the Calmer series and explain how a star’s spectral class can give us clues to its temperature, motion, and chemical composition.