Solar Phase is a novel published in 468. Critics have argued that it would better be described as a collection of short stories with recurring characters, due to the vignette-like nature of its chapters. The story, on the whole, recounts the adventures of six explorers from a futuristic Unda who are pilots of small two-man vessels called jumpskiffs, which use gravitational energy from massive planetary bodies to slingshot themselves to distant star systems. They are also equipped with fictional technologies which ease their entrance into and exit out of planets' atmospheres, allowing for more comprehensive exploration and charting of the unknown. While six characters comprising three jumpskiff teams are featured, the story dwells primarily on Sha Talo, her co-pilot Alcor Laney, and their jumpskiff the Solar Phase. The other jumpskiffs and teams are Elmin Verena and Bell Salras on board the Red Shift, and Jessa Scolly and Bracken Adson of the Nova.

For the most part, the novel explores questions of humanity, identity, and adventure. Unpredictable and dangerous, jumpskiffs have limited control over the path they travel once they are launched, so precise calculations and planning are required in order to make a successful launch and arrival. This risk of death and disappearance gives jumpskiff pilots a kind of reckless allure, and back on Unda, they are treated as celebrities. In space, however, all that falls away. Talo, Laney, and the other pilots are left alone with only their thoughts, one another, and vast and unknown worlds which often do not welcome their presence.

The novel was received to massive acclaim. Predating even the first Undan moon mission, Solar Phase nevertheless proposed a number of technologies and scientific theories which would come to be used in real technology -- notably, the gravitational slingshot the Ingenuity was meant to use to return home after reaching the Cabet asteroid belt. It also created a passion for space in Undans from every island, and members of the Island Union Space Committee have joked at press conferences that several questions about the plot of Solar Phase are asked in their interviews with job candidates, just to make sure they have read it.

Solar Phase was famously published anonymously, but the author later revealed themselves to be one Wim Heiden, a schoolteacher from Tekal. They came out publicly as the author to request that no visual adaptations ever be made of their novel, as the beauty -- in their mind -- of the story was the exercises in imagination the reader was led through as they followed the jumpskiff pilots to strange new worlds. That request has to date been honored.