Coalition of Planets
United Federation of Planets
"Taste that air. Really gets the blood running."
Andoria was a M-class moon orbiting a ringed gas giant in the Andorian system. It was the homeworld of the Andorian and the Aenar races. Andoria took part in talks to form a Coalition of Planets in 2155 and became a founding member of the United Federation of Planets in 2161.
Astronomical Data Edit
Andoria was located in a neighboring system to Vulcan, which led to a series of conflicts between the Andorian Empire and the Vulcans. In 2154, the Vulcan High Command deployed a fleet of 12 starships to Regulus, which lay just outside Andorian sensor range, preparing to attack Andoria. Andoria was also relatively close to the Sol system. In the 24th century, Andoria was located near to the Cardassian border. (DS9: "Tears of the Prophets")
Further Information Edit
In designing her new solarium, Yanas Tigan used tile she imported from Andoria, which she then had hand-painted by this charming old man she met on a trip to the Hovarian Cluster. (DS9: "Prodigal Daughter")
Andoria was inhabited by the blue skinned Andorian species of humanoids, and the Aenar, a subspecies of the Andorians. There was contact between the two sentient species on Andoria in the distant past, but eventually contact was lost and both species only vaguely remembered the other in myths and stories. It was not until around 2104 that contact was re-established between the Andorians and the Aenar. (ENT: "The Aenar")
Andoria was an ice world, with a human-breathable oxygen-nitrogen atmosphere. Andorian cities were underground and took their energy from geothermal activity. The cities were connected to each other by thousands of kilometers of tunnels.
Only during rare heatwaves would the temperature on Andoria rise above freezing, and even then only for a few weeks at a time. During mid-summer, a temperature reading of -28° was not uncommon. (ENT: "The Aenar")
Points of interest:
The Andorian ice caves were a redress of the caverns built for Enterprise's Vulcan trilogy – simply repainted white.
According to writers Judith and Garfield Reeves-Stevens, in a special features segment in ENT Season 4 DVD, the establishment of the Andorian homeworld as a moon orbiting a gas giant was devised to help explain the contradiction of why it was sometimes called Andor and sometimes it was called Andoria, the gas giant being Andor and the moon Andoria.
The Last Unicorn Games Star Trek RPG and Samuel John Ross used information about Andoria, a frozen world first published in Star Trek: The Role Playing Game, for the work The Andorians: Among the Clans. When Mike Sussman and Manny Coto saw this book they "were taken by the striking cover image of an ice-covered Andoria" and went with that interpretation of the planet when it was finally seen in the ENT episode "The Aenar". 
According to Star Trek: Star Charts (pages 19, 36, 52 and 60), Andoria was a was Class M planet located in the Procyon binary star system. This system consisted of a F-type main-sequence star orbited by an A-type main-sequence star. Andoria was identified as the eighth planet. Andoria was the capital of the Andorian Empire, and a founding member of the United Federation of Planets in 2161. The capital of Andoria was Andor, and 38.2 billion people lived on Andoria. Andorians became warp-capable in 1154 A.D. Andoria was located in the Andorian Sector also known as Sector 006. This sector was the sixth explored by Earth ships. In his final voyage in 2120, Zefram Cochrane visited Andoria.
In Worlds of Star Trek: Deep Space Nine, Volume 1, Thirishar ch'Thane and Prynn Tenmei note the differences between the names "Andor" and "Andoria." While Tenmei grew up thinking of ch'Thane's homeworld as "Andoria," ch'Thane grew up knowing it as "Andor." Conversely, ch'Thane grew up thinking of Tenmei's homeworld as "Terra," only to discover that Terrans call it "Earth."