Planetary information Edit
According to Spock, the planetoid was possibly a remnant of a planetary breakup. It was one of 7,000 bodies of sizes running from types A to N in the asteroid belt, 34 percent of which had atmospheres of types H to M. The composition of the planetoid was iron and nickel, and it had an atmosphere that consisted primarily of oxygen and nitrogen with traces of krypton, argon, and neon. The general surface temperature was 75 °F. Gravity was 1 Earth standard. (TOS: "Metamorphosis")
Some time after 2119, a non-corporeal lifeform native to the planetoid, the Companion, discovered the disabled spacecraft of the Human inventor of Earth's warp drive, Zefram Cochrane. The entity brought the ship and its pilot, Cochrane, safely down to Gamma Canaris N. It rejuvenated the eighty-seven year-old inventor and terraformed the planetoid to sustain Cochrane's life.
In 2267, while transporting a terminally-ill Commissioner Nancy Hedford from Epsilon Canaris III to the USS Enterprise, the shuttlecraft Galileo was pulled off course by the Companion and forced to land on Gamma Canaris N. Cochrane had told the entity that he would die of loneliness if he didn't have contact with other Humans. The Companion merged with Commissioner Hedford, moments before her death, and Cochrane remained with her on the planetoid. James T. Kirk promised Cochrane that he would not tell Starfleet that they had discovered him or of what had happened on the planetoid. (TOS: "Metamorphosis"; ENT: "Broken Bow")
In 2293, the location of Gamma Canaris N in the Milky Way Galaxy was labeled in a star chart that was in Captain James T. Kirk's quarters aboard the USS Enterprise-A. (Star Trek VI: The Undiscovered Country, okudagram)
Background information Edit
While "Metamorphosis" stated Cochrane disappeared "a hundred and fifty years ago" (or in 2117), it was established later on, in the Star Trek: Enterprise pilot episode "Broken Bow", that Cochrane was still on Earth in 2119, at the opening ceremony of the Warp Five Complex. The canon-adjacent Stellar Cartography: The Starfleet Reference Library posits his year of disappearance as 2120.