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 50,000 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, it will take much longer for the response to make it back to Earth.

Question

Quizplus · Accepted Answer

The distance to M13 is so vast that even light, which travels at the fastest speed possible, takes a very long time to reach it. The message sent in 1974 was a radio signal, which travels at the speed of light, and it will take about 25,000 years to reach M13. If a response is sent back immediately, it will take another 25,000 years to return to Earth, totaling at least 50,000 years.

In 1974, Astronomers Sent a Message Toward Globular Cluster M13