# Time it would take for sound to travel between moon and earth? [duplicate]

Neil degrasse Tysons documentary series the Cosmos, he mentions that we actually see the moon one second later than it actually is due to the distance of the earth and the moon and speed of light making us see the moon a second behind instead of at real time. If there was someone on the moon clapping (and we ignored other rules of physics like the sound fading and sound waves through space) how long would it take to hear them clapping from Earth?

If you are to say: ignore that there exists no medium for the sound wave to travel and calculate the time it would take for a sound wave in some medium (air, for instance) to travel that distance. It would be calculated as follows: Speed of sound in air is $|v| = 343 \frac{m}{s}$ the distance between the moon and earth is about $384.4 \times 10^6$ meters. So distance divided by the speed is $\frac{384,400,000~{m}}{343 \frac{m}{s}} = 1120699.70845$ seconds, about 13 days.