1. If an alien civilization is located 60 light-years away and they detect the earliest Earth tv transmissions (from ~1930), what year should we receive the first message from the aliens? How did you arrive at your answer?
2. Assume you wanted to have a discussion with a civilization located near the center of the Milky Way Galaxy. What would be the minimum time between sending the signal and receiving a reply?
we live about 2.5x10^20 meters from the center of the galaxy.
Which one is correct below:
4.2 years?
8000 years?
26000 years?
52000 years?
100000 years?
1 million years?
Earliest possible time would be 60 years from now .
B)
.2.5*10^20 meters / 3* 10^8 meters/second = 26406.7 or approx. 26000 years (to 2 sig figs) for light to get to the center of the galaxy.
Then the light has to travel for another 26000 years to get back so that's a round trip time of 52000 years.
1. If an alien civilization is located 60 light-years away and they detect the earliest Earth...
17. The nearest star is approximately four light-years from Earth. Imagine that an alien civilization has been discovered there. You send them a message. How long do you have to wait for their reply, assuming they respond immediately?