Light plays a significant role in the action and in the mise-en-scène of the novel. It suggests both transformation—through the recurring motif of sunrise and moonrise—and enlightenment. The novel begins, for example, with “the first faint glow of dawn [creeping] into the cave Moon-Watcher” (3). This takes place within the section of the novel called “Primeval Night,” underlining the idea that this light dawning is a metaphor for dawning intelligence and the evolution of “mind.”

The extraterrestrial lifeforms who sowed the seeds for human evolution themselves evolve into intelligence captured in light, leaving corporeal existence behind. Bowman encounters something like this when he travels through the Star Gate: “The crystalline planes and lattices, and the interlocking perspectives of moving light” (219). The monoliths they leave behind are also characterized by plays of light and by relationship with sunrise. The first monolith is described as “a rectangular slab […] made of some completely transparent material; indeed, it was not easy to see except when the rising sun glinted on its edges” (4). The second monolith is activated by sunrise, linking the light of dawn to a new stage in human development.

This image recurs toward the end of the novel, when the action takes place on the surface of a red dwarf star: “Dying? No—that was a wholly false impression, born of human experience and the emotions aroused by the hues of sunset” (203).