QUESTION #608
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How long did radio commands take to travel from the Earth to Voyager as it passed Neptune?

Asked by: Amanda

Answer

Well, radio waves are electromagnetic waves, so they travel at the speed of light, which is about 3x108 m/s. According to https://www.physlink.com/reference/astrophysical.cfm , Neptune is 4.5x1012 m away from the sun, and since Earth is only 1.5x10^11 m away from the sun, I'll just assume that we're about 4.5x1012 m away from Neptune. This means that the radio signals took (4.5x1012 m) / (3x108 m/s) = 15,000 seconds (or a little over 4 hours) to get to the Voyager.
Answered by: Gregory Ogin, Physics Undergraduate Student, UST, St. Paul, MN