Thuria (known to Earthmen as Phobos, and by its natives as Ladan) is the nearer moon of Mars. About 5,800 miles distant from Mars, she makes a complete revolution around the planet (from west to east) in just over 7.5 hours. The moon is typically referred to using feminine pronouns.
Thuria has her own inhabitants, the Tarids and the Masena, who both refer to their home as Ladan. The former are white-skinned humanoids with blue hair and powerful telepathic abilities, which they have long used to make themselves invisible to the people of Mars. The Masena are grotesque humanoids with one eye in the center of there foreheads and two mouths; the lower is lipless with the surrounding skin serving as the gums for a set of teeth, which give the creature a hideous perpetual grin, while the upper mouth resembles a sphincter with lips.
Thuria is also inhabited by various animals, some of which are predators that are greatly feared by both the Tarids and the Masena's. They are not named or described in much detail.
- While the novels make mention of Thuria illuminating the night sky of Barsoom, the real Phobos is actually one of the least reflective bodies in the Solar System.