Remember that 10 Angstroms = 1 nm, so 4000 Angstroms = 400 nm = blue light ...

Print a copy of the spectrum of the planetary nebula PN G000.2+06.1, which is shown at the top of this lecture. On the printed copy,
- identify and mark the emission lines which are due to Balmer transitions of hydrogen atoms; you should be able to find at least 3 or 4
- for each of these lines, write down the initial energy level and the final energy level involved in the transition (i.e. for the line at 656 nm, you would write "initial n=3, final n=2")
Look at the stellar spectrum below.
- Estimate the temperature of this star.
- Sodium atoms have the following energy levels: (sort of -- I've assigned some new numbers)
```
            n          energy (eV)
          -------------------------
            1           -5.14
            2           -3.04
            3           -1.96
            4           -1.52
          -------------------------
        
```
  One of the strongest lines in the spectrum above is due to a transition in sodium atoms. Which one is it? What is the wavelength, and what are the levels involved?