- For similarly named articles, see Miri (disambiguation).
Miri's homeworld, so named after Miri, a native of the planet, was a Class M planet located in the 70 Ophiucus star system of the Beta Quadrant. It is a parallel universe version of Earth, which had briefly found itself in the main timeline due to temporal instability. (DTI novel: Forgotten History)
In the 1950s, the world's scientists attempted to prolong the race's life; however, their experiments killed the entire adult population. The growth and development of the planet's children (who, in the aftermath of this tragedy, began to call themselves "Onlies") was slowed to the rate of one month per century, but the older survivors would age rapidly and die upon reaching puberty.
The planet was visited in 2266 by the USS Enterprise, where the landing party members were struck by the same affliction. Dr. Leonard McCoy was successful in finding a way to counteract the rapid aging. (TOS episode: "Miri")
The homeworld of Miri and her friends, the Onlies, appeared at first to be a simple copy of Earth; however, it was later discovered that Miri's homeworld was actually Earth itself, of an alternate timeline. Miri's Earth had briefly drifted into the main universe, due to instability in the local sector of space. In June 2274, the planet returned to its original timeline. (DTI novel: Forgotten History)
- An alternate version of the later fate of Miri's homeworld is given in the third issue of Marvel's Star Trek: Untold Voyages comic series, where the planet persisted in the Prime universe even into the year 2275. (TOS - Untold Voyages comic: "Past Imperfect")
Various sources have given different names and planetary numbers for the planet. The novelization of the episode by James Blish states that the planet is the fourth planet of the 70 Ophiucus system. This story also ignores the stated idea that the planet is a parallel Earth, and states that it was an old Earth colony which was established in the early 2100s and forgotten about. The TOS novel The Cry of the Onlies gives the planetary designation of Juram V and supports the parallel Earth theory. The reference book Star Charts gives the planet the designation of Miri and gives a designation of FGC-347601 III, making it the third planet of the system. In the older Star Trek Maps it was the third planet in the UFC 347601 system. The novel Preserver calls it Site 2713 and describes it as one of three Earth duplicates created by the Presevers. Forgotten History provides a different explanation: Miri's homeworld is actually Earth of a parallel timeline.