The nearest star beyond the sun is Alpha Centauri which is 4.21016 meters away If you were to receive a radio message from this star today how long ago would it have been seen?

Answer 1

Actually the nearest star (except for the sun) is Proxima Centauri is next at 4.3 light-years from the Earth. It would take 3.4 years at one light-year/year for radio waves to reach Earth from there. This is because the radio waves are travelling in a vacuum and all electromagnetic wave in a vacuum travel at "C" AKA the speed of light.

Answer 2

Actually the nearest star (except for the sun) is Proxima Centauri is next at 4.3 light-years from the Earth. It would take that long for radio waves to reach Earth from there.