How long does it take for a radio signal to go from Earth to Mars?
Asked by: Richard Boulais
Radio signals are electromagnetic waves,
such as light or X-ray. The speed of
electromagnetic waves in vacuum, is 300000km/sec
In order to calculate the time of travel with this
speed from Earth to Mars, we need to know the
When the Mars and the Earth are at the opposite
sides of the Sun, the distance is the largest:
approximately: 378 million km. The time needed
for an electromagnetic wave to cover this
distance is approximately: 21 minute.
The closest distance between Mars and Earth is 78
million km, the time in this case is: 4.3 min.
So the time of travel between Earth and Mars is
between 4.3 minutes and 21 minutes, depending on
the actual distance between the two planets.
Answered by: Ferenc Szekely, Ph.D., Physicist, ELTE, Budapest, Hungary