Sphinx, also called Manticore A-IV, was one of the three inhabited planets of the Manticore System, and the homeworld of the treecats. It orbited the system's primary star along with the planet Manticore.
Sphinx was located further away from its star than Manticore. As a result, the climate was on the cooler side of Terran norm. Also due to its higher orbital radius, the Sphinxian year was roughly five times as long as Earth's year, with a corresponding increase in the length of the seasons. The planet's gravity was 1.35 times as high as Earth's.
Sphinx days were 25.62 T-hours long, and there were 1,783.28 days in a Sphinxian Year. There were 1,903.65 T-days in a year, and one Sphinx year equalled 5.22 T-years. The Sphinx year was divided into 46 months, 35 of 39 days and 11 of 38 days. The shorter months fell into even-numbered months from 12th month to 32nd month, with a leap year every seven years. Sphinx had a fourteen-degree axial tilt. (UHH)
Planetary geography and climate
Sphinx icebergs were proverbially unapproachable. (HH1)
Sphinx had particularly cold winters. (HH2) The Tannerman Ocean was a large body of water located on the planet. The Copperwalls were a mountain range. Because of the planet's distance from Manticore's sun, the planet had a very active carbon dioxide cycle that helped maintain the atmosphere and environment. (HH3)
The atmosphere was composed of 83 percent nitrogen, 15 percent oxygen, 1 percent argon, and 1 percent carbon dioxide, making it breathable for humans. (infodump)
In 1568 PD, following ratification of the Ninth Amendment to the Manticoran constitution, treecats were given basic rights under Manticoran law, and one-third of the land on Sphinx was protected as treecat habitat in perpetuity.
In February 1922 PD, the space station Vulcan was completely destroyed by the Mesan Alignment Navy as part of Operation Oyster Bay. Debris from the station rained down onto the surface of Sphinx, destroying the city of Yawata Crossing, damaging many other habitats, and wiping out the Black Rock Clan of treecats save for one survivor. (HH12)
Treecats were a sentient species native to the planet. The rabbit adapted to Sphinx's environment very well after being introduced by human settlers. (HH2) Some of the native plant life are crown oak and picket wood which grow on the lower elevations. (HH3)
- Stephanie Harrington – Discoverer of the treecats.
- Lionheart – The first treecat to bond with a human.
- Dianchect – The first treecat to bond with a member of the Royal Family of Manticore.
- Sings Truly – Treecat who proposed continued bondings with humans.
- Salvatore Hammerwell – Manticore's greatest composer (HH2)
- Honor Harrington – an officer of the Royal Manticoran Navy (HH1)
- Samantha – proposed that treecats immigrate to other planets and reveal more of their intelligence.
- Sorrow Singer - Last surviving member of the Black Rock Clan.
- As of 1920 PD