A planet's density can be measured by combining :

A planet's density can be measured by combining
 
  A) Doppler and astrometric observations.
  B) Doppler and transit observations.
  C) spectral observations of the planet's atmosphere.
  D) any method that measures the gravitational tug of the planet on the star.
  E) direct imaging from the new generation of space telescopes.

Question 2

A mountain top is an especially good site for infrared telescopes since:
 
  A) there you are closer to celestial objects.
  B) you are above most of the carbon dioxide and water vapor in the atmosphere.
  C) the cold weather helps the sensitivity of infrared detectors.
  D) less air above means better seeing in many cases.
  E) All of the above are factors.

Question 3

Most SETI searches are done at:
 
  A) X-ray wavelengths.
  B) infrared wavelengths.
  C) visual wavelengths.
  D) radio wavelengths.
  E) gamma wavelengths.

Question 4

Most interstellar dust grains are produced in
 
  A) the Big Bang.
  B) the interstellar medium.
  C) the atmospheres of red giant stars.
  D) supernova explosions.
  E) the solar nebula.