Adrian

Adrian is the third planet orbiting Tau Ceti, named by Ryland Grace after Rocky's mate. It is a pale-green super-Earth with a thick carbon-dioxide atmosphere, and it serves as the Astrophage homeworld—the source of the predator Taumoeba that ultimately saves both Earth and Erid.

Discovery and Naming

Rocky, who had spent forty-six Earth years alone in the Tau Ceti system, surveyed the system thoroughly before Grace arrived. He cataloged six planets, noting their size, mass, positions, orbital characteristics, and general atmospheric makeup through astronomical observations from the Blip-A. When Grace and Rocky began working together, Grace insisted that Rocky, having been there first, should name the planet. Rocky chose the name of his mate, a sequence of musical chords. Grace, unable to pronounce the Eridian name, assigned the English word "Adrian" to represent it. Rocky had never mentioned having a mate before, and Grace learned that Eridians are hermaphrodites who mate for life; Rocky was uncertain whether his mate had taken a new partner during his long absence.

Physical Characteristics

Adrian is a super-Earth with 3.93 times Earth's mass and a radius of 10,318 kilometers—almost double Earth's. Its surface gravity is 1.4 g, and it orbits Tau Ceti with an average velocity of 35.9 kilometers per second. The planet appears pale green from space, with dark and light bands of green wrapping around it, reminiscent of Jupiter and Saturn, though it is a rocky world rather than a gas giant. Its density, calculated from Rocky's precise measurements of radius and mass, confirms it is far too dense to be composed only of gas. A thick atmosphere, 91 percent carbon dioxide, 7 percent methane, 1 percent argon, and trace gases, obscures the surface entirely from visible-light observation. The high methane content initially puzzled Grace, as methane breaks down quickly in sunlight, but the explanation emerged when life was discovered on the planet.

The Astrophage Homeworld and the Discovery of Taumoeba

Adrian is not merely a planet infected by Astrophage—it is the Astrophage homeworld. When Grace analyzed samples collected from the Petrova line using the External Collection Unit, he found not only Astrophage but a diverse array of translucent cells, bacteria-like organisms, amoeba-like creatures, and other microorganisms. The population of Astrophage traveling toward Adrian was equal to the population traveling away from it, which was unexpected because Astrophage should breed on the planet and produce twice as many returning cells. Rocky immediately understood the implication: some life on Adrian eats Astrophage, keeping the population in balance. This predator, which Grace named Taumoeba, is an amorphous amoeba-like organism that envelops and consumes Astrophage, disabling their ability to absorb heat and light energy. The presence of this predator explained both the population balance and the methane in Adrian's atmosphere, as methane is a waste product of Taumoeba digestion.

Narrative Significance

Adrian is the key to the entire mission. The discovery that Taumoeba naturally preys on Astrophage provides the solution to the Astrophage crisis threatening both Earth and Erid. Grace and Rocky breed nitrogen-resistant strains of Taumoeba in the lab, eventually creating Taumoeba-82.5, which can survive in the atmospheres of Venus and Threeworld. Grace sends samples of this engineered predator to Earth aboard the beetles, and Rocky carries a supply back to Erid. Years later, news reaches Erid that Sol has returned to full brightness, confirming that the Taumoeba successfully eliminated Astrophage from the solar system. Adrian thus functions as the narrative's hidden salvation—a seemingly ordinary planet that turns out to be the origin of both the problem and its cure.