When white light passes through a cool cloud of gas, we see
A) visible light.
B) infrared light.
C) thermal radiation.
D) an absorption line spectrum.
E) an emission line spectrum.
Question 2
If we had sent a radio signal to an advanced civilization in 2006 which is located in the zeta reticuli star system approximately 39 light-years away and the signal was immediately replied to, when would the reply arrive back at Earth?
A) 2084
B) 2012
C) 2045
D) 2039