How Long Does it Take to Call Mars?
Alexandra: Suppose this boy on Earth, was asking this girl on Mars, to go out on a date. Just work with me here a second. First, he asks the question:
Alfredo: Uh, hey, will you go out with me?
Alexandra: On average, Mars is about 225,000,000 kilometers from Earth, The speed of the radio wave carrying the message is the speed of light, or 300,000 km/sec. At that speed, with a straight shot, the message will take about 12.5 minutes to make it to the girl.
The girl answers… (Luz on surface of Mars) and her signal, again traveling the speed of light, must make the roughly 225,000,000 kilometer journey back to Earth.
All is said and done, our Romeo here can expect about a 25 minute wait to get his answer.
Luz: (over the phone voice) Yes I'll go out with you! But I won't be back on Earth till next year!
End of Transcript
NASA Brain Bite BB1301B