Two astronauts are 2.40 m apart in their spaceship. One speaks to the other. The conversation is transmitted to earth via electromagnetic waves. The time it takes for sound waves to travel at 343 m/s through the air between the astronauts equals the time it takes for the electromagnetic waves to travel to the earth. How far away from the earth is the spaceship Number Units Solution time taken by sound to travel 2.40 m, t = 2.40 / 343 s spaceship is at the distance at light can travel in time t. distance = speed x time = (3 x 10^8 ) (2.40 / 343) = 2.099 x 10^6 m.