1. If an alien civilization is located 60 light-years away and they detect the e

Question

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?

Explanation / Answer

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.

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