Final answer:
The length of time Apollo 13 was out of communication with Mission Control during its orbit around the Moon's far side is commonly known to be about 45 minutes, but this specific information is not found within the provided text.
Step-by-step explanation:
The duration for which Apollo 13 was out of communication with Mission Control while on the dark side of the Moon isn't directly provided in the information above. However, it is known that during visits to the Moon, there was a communication blackout while the spacecraft was behind the Moon, out of direct line of sight with Earth. We can understand the concept of radio signal delays by considering that light (or radio waves) takes approximately 1.3 seconds to travel the distance between Earth and the Moon. Given this information, the delay experienced during communications between Mission Control and the Apollo astronauts was about 3 seconds to account for the round trip of signals. Although we know these facts about signal travel time, the specific length of time that Apollo 13 was out of communication is not mentioned in the reference provided. However, commonly known information indicates that the communication blackout period for Apollo missions while orbiting the Moon lasted for about 45 minutes.