A) Visible light B) Infrared waves C) Ultraviolet waves D) Radio waves E) [Both A and D above.] 5. Which of the following part(s) of the electromagnetic spectrum penetrate the atmosphere well? A) Visible light B) Infrared waves C) Ultraviolet waves D) Radio waves E) [Both A and D above.] 6. What is the main reason that astronomers (and other scientists) almost always use the Kelvin (absolute) temperature scale, rather than the Celsius or Fahrenheit scales? A) The scale has a physically meaningful absolute zero of temperature. B) The temperature of freezing and boiling water are easier to remember. C) Calculations are easier on the Kelvin scale. D) The size of each degree (or unit) of temperature is more convenient.