Somnium

What it is

Somnium ("The Dream") is a Latin novel written by Johannes Kepler, developed from an early student thesis and later published after his death in 1634 by his son Ludwig Kepler. It tells a fictional story of a boy who learns of a journey to the Moon, called Levania, with vivid descriptions of how the Earth would look from there.

Why it matters

Kepler used the fictional story as a way to defend and explain the Copernican idea that the Earth moves, imagining how things would look from the Moon's perspective. The work is considered one of the earliest works of science fiction, and later thinkers such as Carl Sagan and Isaac Asimov praised it as a pioneering blend of scientific thinking and imaginative storytelling.

Look closer

• Why might Kepler have chosen to explain a scientific idea through a fictional dream rather than a plain argument?
• What parts of the story seem based on real astronomy, and what parts are purely imaginative?
• Why was the book not published until after Kepler's death?