Theremon is a journalist working for the Saro City Chronicle. He values objectivity and routinely balances his reports by seeking counterarguments from various experts. When a religious group issues apocalyptic predictions, Theremon approaches the astronomers of Saro University to provide scientific refutations. He views religion as an outdated institution and strongly opposes any collaboration between scientists and religious leaders.

Siferra is an ambitious archaeologist employed by Saro University. She discovers the buried Hill of Thombo, a site containing layers of ruined civilizations that were each destroyed by fire at regular intervals. She worries deeply about her professional legacy and fears her archaeological discoveries might accidentally validate local religious prophecies.

Beenay is a dedicated junior astronomer at the Saro University Observatory. He closely studies the planetary orbits of Kalgash and discovers a massive mathematical anomaly that threatens to disprove his mentor's foundational theories. He struggles to balance his obsessive professional life with his personal commitments.

Sheerin is a university psychologist studying the mental impacts of darkness on a planet accustomed to perpetual sunlight. He investigates a controversial amusement park attraction called the Tunnel of Mystery. By experiencing the pitch-black ride himself, he suffers severe claustrophobia and begins formulating theories about how the population would react to a planetary eclipse.

Athor is the esteemed director of the Saro University Observatory. He developed the Theory of Universal Gravitation, which serves as the foundation for modern astronomical research on Kalgash. Faced with new orbital data, he must reevaluate his life's work and consider whether an invisible satellite is affecting the planet.

Folimun is a public relations officer and emissary for the Apostles of Flame. He operates out of a golden tower in the affluent quarter of the city. He defends his group's ancient scriptures, warning the public about an impending divine judgment brought on by heavenly flames called Stars.

Raissta is an academic and the niece of the psychologist Sheerin. She is in a relationship with Beenay, though she frequently expresses frustration over his tendency to prioritize astronomical research over their time together.

Mondior is the prophesied leader of the Apostles of Flame. He publicly declares that the world will end in fourteen months when the gods judge humanity and destroy civilization with the Stars.

Yimot is a younger astronomer working at the Saro University Observatory. He assists Beenay in replicating complex gravitational calculations to verify orbital anomalies in the planet's solar system.

Faro is a junior astronomer at the observatory who works closely with Yimot and Beenay. He tests new theories regarding Kalgash's orbital movements and helps project historical planetary trajectories.

Thilanda is an astronomer at Saro University. She assists the primary research team by projecting the historical and future trajectories of Kalgash's six suns, providing crucial data for predicting an eclipse.

Balik is an archaeologist who works alongside Siferra 89. He documents the excavation at the Hill of Thombo through photography and expresses a personal interest in Siferra, attempting to mix their professional work with a romantic vacation.

Mudrin is a paleographer at Saro University. He is tasked with analyzing and deciphering the ancient scripts found on the tablets recovered from the Thombo excavation site.

Kelaritan is the director of a psychiatric institute in Jonglor City. He facilitates Sheerin's investigation into the severe psychological trauma experienced by riders of a local amusement park dark ride.

Cubello is a defensive lawyer representing the Jonglor Centennial Exposition. He is highly concerned with the legal and financial liabilities surrounding the theme park's controversial dark ride, prioritizing profit and public relations over safety.

Harrim is a survivor of the Tunnel of Mystery attraction. His severe psychological reaction to being enclosed in total darkness leaves him hospitalized and serves as an early case study for Sheerin's psychological research.

Varitta is an engineer who helped design the Tunnel of Mystery attraction at the Jonglor Centennial Exposition. She provides Sheerin with an abort switch to ensure his safety during his investigative ride.

Nyilda is the wife of Athor 77. She cares deeply for her husband's well-being and worries about the physical toll his obsessive astronomical research takes on his health.

Liliath is a colleague of Sheerin at Saro University. She receives him after his travels and updates him on the current search efforts of his peers.

Altinol is a former corporate officer in Saro City. Known for his involvement in a past corruption scandal, he possesses a strong and authoritative personality that aids his survival instincts.