Approximately how soon might we expect an immediate response from a civilization that received the signal we sent to the globular cluster M13 (21,000 light-years away) in 1974?
A) 84,000 years
B) 21,000 years
C) 10,500 years
D) 42,000 years

Question

Quizplus · Accepted Answer

The signal would take 21,000 years to reach M13, and any response would take another 21,000 years to travel back to Earth, totaling 42,000 years.

Approximately How Soon Might We Expect an Immediate Response from a Civilization