In 1974, astronomers sent a message toward globular cluster M13. If life exists there, and it returns our signal, we won't receive it for at least another 44,000 years. Why?
A) It will take that long for the space probe carrying our signal to reach the life forms there.
B) Based on the age of the stars in M13, we anticipate it would take that long for a civilization to evolve enough to interpret and respond to our signal.
C) M13 is far enough away that even light takes a very long time to reach it.
D) It will take that long before our Solar System and M13 are properly aligned again.
E) The universe will have expanded substantially after M13 receives our message, therefore taking much longer for their response to make it back to Earth.

Question

Quizplus · Accepted Answer

M13 is located about 22,200 light-years away from Earth, which means that even light (the fastest known thing in the universe) takes 22,200 years to reach it. Therefore, any signal we send would also have to travel that same distance, so it would take at least 44,000 years for us to receive a response.

In 1974, Astronomers Sent a Message Toward Globular Cluster M13