# Is there a term that references the time delay between two objects communicating in space, especially at great distances?

When communicating at distance in space (such as Earth communicating to a craft orbiting Mars), the communication experiences a time delay. My research indicates this delay maybe called "One-Way Light Time" (OWLT) or One-Way Speed of Light Time: https://en.wikipedia.org/wiki/One-way_speed_of_light

Is this the correct term and does it cover extreme distances as well, such as covering distances between solar systems, across the milky way, etc?

• In Sci-Fi this concept is often shortened to "light lag" which I think is a rather concise term (the only ambiguity being if it is round-trip or one-way lag). For example, someone might say, "The light lag of one second between Earth and the moon makes conversation uncomfortable." – Dragongeek May 19 '20 at 17:17

NASA's Deep Space Network calls it round-trip light time.