How do you work out how long radio waves take to get from Earth to Pluto?
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Answer by Don Dfoofnik
Confidence votes 165K
There are three kinds of answers: ones that are mostly right, ones that are mostly wrong, and those that once were right but now are wrong.
Radio waves travel at essentially the speed of light in space, and that is a known value. So if you know the exact distance between Earth and Pluto, you can divide the distance by the speed to see how long a radio signal from Earth will take to reach there. Of course, during the year the time will vary, because the distance will vary.
Average distance of Pluto from the Sun: 5.874 billion kilometers
Average distance of Earth from the Sun: 149.6 million kilometers
Distance from Earth to Pluto ~ 5.724 billion kilometers
Speed of radio signal (light): 299792.456 kilometers per second
Dividing: 5.724 x 109 / 2.998 x 105 = 1.91 x 104 seconds = 5.3 hours
(and of course, to send it and receive a reply would take twice that time)
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Absolute closest distance (4.285 billion km) -- 4.0 hours
Absolute farthest distance (7.463 billion km) -- 6.9 hours
Average distance of Pluto from the Sun: 5.874 billion kilometers
Average distance of Earth from the Sun: 149.6 million kilometers
Distance from Earth to Pluto ~ 5.724 billion kilometers
Speed of radio signal (light): 299792.456 kilometers per second
Dividing: 5.724 x 109 / 2.998 x 105 = 1.91 x 104 seconds = 5.3 hours
(and of course, to send it and receive a reply would take twice that time)
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Absolute closest distance (4.285 billion km) -- 4.0 hours
Absolute farthest distance (7.463 billion km) -- 6.9 hours
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Then You add in the time it takes NASA Engineers to make coffee and wait until the CIANSAMILITARYINTEL have gone through and Redacted all the stuff they don't want the Public to see and ship the Images via Pack Camel in the name of mooselimb diversity to NASA and there You have the answer.