Celestial Matters is a science fantasy novel by American writer Richard Garfinkle, set in an alternate universe with different laws of physics.

In this world, the Delian League (Greeks) and Middle Kingdom (Chinese) have been fighting a war for nearly a thousand years, ever since the time of Alexander the Great when the warrior-culture of Sparta and the Athenian Akademe were fused into a half-world conquering force.

The story is narrated by Aias of Tyre, a scientist of the Delian League, who is preparing to embark on Project Sunthief as scientific commander.

The Middlers have been assassinating Delian generals and politicians, so Aias is assigned a bodyguard, Captain Yellow Hare of Sparta, a woman of Xeroki ancestry.

Aias' old friend Ramonojon, a mathematician, has expressed doubts about the rightness of annihilating an entire city and is viewed with dark suspicion by Anaxamander, the heroic military commander of the project.