If you speak via radio from Earth to an astronaut on the Moon, how long is it before you can get a reply?

Short Answer

Expert verified
It will take about 2.56 seconds to receive a reply.

Step by step solution

01

Find Distance from Earth to Moon

According to NASA, the average distance from the Earth to the Moon is about 384,400 kilometers.
02

Understand the Speed of Light

The speed of light in a vacuum, like space, is approximately 299,792 kilometers per second.
03

Calculate the Travel Time

To find how long it takes for light to travel to the moon, use the formula: time = distance / speed. So, time = 384,400 km / 299,792 km/s = approximately 1.28 seconds. However, this is only the one-way trip. The radio message has to go to the Moon and then return back to Earth, so this time should be doubled, giving a final time of approximately 2.56 seconds.

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