(covers information from several alternate timelines)
Archer IV was an inhabited M-class planet and the fourth orbiting the primary 61 Ursae Majoris, which had two moons. The first M-class world surveyed by the crew of the NX-class starship Enterprise NX-01 in 2151, it became named for Starfleet Captain Jonathan Archer.
Archer IV's atmosphere consisted of seventeen percent oxygen and eighty-one percent nitrogen, also including trace elements of nitrogen dioxide and chloromethane. Boasting a fertile landscape including vast grasslands and snow-topped mountains, Archer IV was inhabited by a wide array of plant and animal life, including nocturnal marsupials, scorpion-like arachnids, fireflies, and fish. The planet, however, supported no indigenous intelligent lifeforms upon its discovery.
Initial landing parties in 2151 experienced rapidly changing weather patterns and fast-moving storms. Such inclement weather spread toxic pollen, released by the diverse fauna and flora, causing in Human and Vulcan visitors paranoia and decreased cognitive function. With no refuge from the effects of the pollen, the planet was considered to be uninhabitable. (ENT: "Strange New World", "Home", "Two Days and Two Nights")
Shortly before Travis Mayweather visited the ECS Horizon in January 2153, Charles Tucker III handed him a PADD which included a picture of Mayweather standing in a green field on Archer IV. (ENT: "Horizon")
Archer IV remained uninhabitable throughout the 22nd century. In the early 2200s, however, an antidote for the pollen was discovered. By 2268, more than seven hundred million people populated the planet. (ENT: "In a Mirror, Darkly, Part II" production art)
In an alternate timeline, Archer IV was the site of a battle in the Federation-Klingon War during the mid-2360s. At this engagement, the Enterprise-D emerged victorious against the Klingons. During a later confrontation with the Klingons as a location when the USS Enterprise emerged from a temporal rift, a small Klingon task force arrived at the location uncloaked, prompting Commander William T. Riker to respond, "They shouldn't be so confident after the pasting we gave them on Archer IV." (TNG: "Yesterday's Enterprise")
Background information Edit
The scene descriptions in the script for "Strange New World" originally twice described this planet as a "lush, blue-green planet," prior to the teleplay detailing aspects of the planet more closely. In an unused line of dialogue from the script, the planet's mountains were described, by Crewman Ethan Novakovich, as seeming to be taller than the Himalayas.
In "Two Days and Two Nights", the NX-class Enterprise set a record by becoming the first Starfleet ship to travel ninety light years from its homeworld. Archer IV was visited by Enterprise prior to its historic feat, suggesting it was less then ninety light years from Earth.
The Star Trek: Enterprise fourth season episode "In a Mirror, Darkly, Part II" revealed the connection between "Strange New World" and "Yesterday's Enterprise" through text in Jonathan Archer's personnel file. The file indicated that the planet orbited 61 Ursae Majoris, a fact also established in the script of "Home".
Star Trek: Star Charts (pp. 60, 63, "United Federation of Planets I"), which came out prior to this connection being made, stated the planet to be Loracus Prime, which actually was a misinterpretation of a prop seen early in the episode "Strange New World". As a consequence, the star "Archer", which Archer IV supposedly orbited, was placed near Klingon territory, several hundred light years away from Sol. The more recent Stellar Cartography: The Starfleet Reference Library ("Federation Historical Highlights, 2161-2385") corrected this error. The system was identified as Archer1. Both sources locate the 61 Ursae Major system in the Beta Quadrant. In the late 24th century, this was a Federation system.
The Star Trek Encyclopedia (4th ed., vol. 1, p. 38) states the exterior scenes, depicting the planet's surface, were filmed on location at the Golden Oak Ranch (aka the Disney Ranch) in Santa Clarita, California. The cavern interiors were filmed on location at the Bronson caves in Los Angeles.
The Pocket DS9 novel The 34th Rule states Archer IV was the source of a beverage called Archerian slug wine. Although the novel was published two years before the episode aired, a species of slug-like creatures appear in "Strange New World".