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

Question

Quizplus · Accepted Answer

Because the star system is located 39 light-years away, it would take the radio signal 39 years to reach the civilization in zeta reticuli. Therefore, if the signal was immediately replied to, it would take another 39 years for the reply to reach Earth. Adding 39 years to 2006 gives us 2045. However, we must remember that the question asked for when the reply would "arrive back" at Earth, which means we need to add another 39 years for the reply to travel back. Therefore, the answer is 2006 + 39 + 39 = 2084.

If We Had Sent a Radio Signal to an Advanced