The Earth's atmosphere blocks most forms of electromagnetic ...

[folubunmi]

The Earth's atmosphere blocks most forms of electromagnetic radiation from entering except for ___________________ _ and ___________________ _.
 
  Fill in the blank(s) with correct word

Question 2

If the spiral density wave were the only thing producing spiral arms, it would be expected that
 
  a. all spiral arms would be gas and dust free.
  b. all galaxies would have only two smooth spiral arms.
  c. the Milky Way would show and irregular pattern of short arms
  d. the Milky Way wouldn't have any spiral arms.
  e. the halo component of the Milky Way would show spiral arms as well.

[rnehls]

Answer to Question 1

visible light; radio waves

Answer to Question 2

B

[folubunmi]

Excellent

[coreycathey]

Great answer, keep it coming