Chapter 3

123456789101112131415
Across
  1. 1. the distance to an imaginary star
  2. 3. very small stellar parallaxes
  3. 5. least possible energy
  4. 6. used to classify stars into nine principal types
  5. 9. measuring the distances to nearby stars
  6. 10. elements that have its own unique set of allowed electron orbits
  7. 12. problem of ascertaining the actual positions and motions of stars
  8. 13. atom that radiates
  9. 14. the apparent change in a star’s position
  10. 15. each elements atoms have a nucleus with a unique number of positively charged protons
Down
  1. 2. the analysis of spectra
  2. 4. distance to the star
  3. 7. first-magnitude star exactly 100 times bigger than a sixth-magnitude star
  4. 8. an electron in a particular orbit
  5. 11. atom is unstable