Astronomy

2. used for measuring distances in the sky
5. atom left with positive charge
8. distance to an imaginary star whose parallax is 1 second of arc
9. classify stars into nine principal types
10. energy required to remove it from the atom
11. produced when electrons jump from higher energy levels back down to lower energy levels
12. atom with least possible energy
13. spectrum of stars
15. pellet of light
16. smallest part of a chemical element

1. lines named after Joseph von Fraunhofer
3. produced when an atom of chemical element absorbs light and the electrons jump out to higher energy levels
4. analysis of spectra
6. tells the chemical element that it absorbs
7. electron orbits
14. position and motion of stars