What is the name of Copernicus's earlier manuscript summarizing his heliocentric theory?

Copernicus's earlier manuscript summarizing his heliocentric theory was called Commentariolus, meaning “Little Commentary.” It was a brief Latin outline of the revolutionary idea that Earth moves and that the planets orbit the Sun.

Copernicus wrote the manuscript by about 1514 and circulated copies privately among friends and colleagues. Unlike his later major work, it was not printed during his lifetime. The manuscript offered a compact framework rather than the extensive calculations and tables that would fill De revolutionibus orbium coelestium, published in 1543.

The Commentariolus stated seven central postulates. These included Earth's rotation, Earth's annual orbit around the Sun, the fixed stars' apparent daily motion being caused by Earth's rotation, and the idea that retrograde planetary motion is an apparent effect of Earth's movement. The Moon remained in orbit around Earth while traveling with Earth around the Sun.

The manuscript became obscure after copies circulated in the sixteenth century. Its existence was known indirectly until a surviving copy was discovered and published in the nineteenth century. De revolutionibus was therefore the mature book, not the earlier summary.