light-second n.

The longest wireless waves ever produced are some number of light seconds long.

Astronomic units of distance now in use, ‘light second’, ‘light hour’, etc., are commensurable with the units proposed, the first being one billion times the fundamental unit of length.

Expressing these large and small measures with reference to the velocity of light, we have an illustration of the scale of the astronomer’s universe—his measures range from the trillionth of a billionth part of one light-second, to more than a thousand light-centuries.

The great control ships directed the dive of the radio-control-ships, making the distance one-twentieth part of a light second.

One fleet was not two parsecs from Vega itself; another had captured Luna and hovered one light-second above the Earth.

Let us select a foot as common measurement, and we shall define a foot as a certain fraction of a light-second so that any measurement system can be converted to feet.

On the Apollo voyages, for the first time, men traveled more than a light-second away from Earth.

Another light-second and a half, and she could bring the Manty under fire with her energy weapons.

We have hundreds of millions of people living within a few light-seconds of each other.

Yes, NASA gave the OK for direct communication an hour ago. We’re only 35 light-seconds apart, so we can talk in near-realtime. I just set up the system and I’m testing it out.