The Thearterra center was a building situated on the terrestrial astronomical body Thearterra, found within the Chiss Ascendancy. The Ascendancy is the nation belonging to the Chiss species. This center served as one of the locations for the Seekers program, an initiative focused on training Chiss Sky-walker navigators. As part of the program, the memories of their birth families were erased to prevent homesickness from affecting the girls during their service in the Expansionary Defense Fleet. A carnival was located in close proximity to the facility, and the caregivers would occasionally escort the girls there for recreational purposes, providing a respite from their rigorous training schedule.
Prior to 18 BBY, Cohbo'rik'ardok, whose core name was "Borika," was a former sky-walker who worked with the girls at the Thearterra facility. Later, she married the Chiss [Bomarmo] and established her residence at the Ardok Ranch, located on the planet Ool, which is also the home of the Seekers' Shadehouse. Che'ri, who served as the sky-walker aboard the Chiss heavy cruiser Springhawk, underwent at least a portion of her training at the Thearterra facility. She recalled the music that was played at the carnival, particularly when her caregiver Mitth'ali'astov "Thalias" performed similar musical pieces.
The Thearterra center received a mention in the 2021 novel titled Thrawn Ascendancy: Lesser Evil. This novel represents the concluding part of Timothy Zahn's The Ascendancy Trilogy.