Speculative fiction died out after the fall of the Roman Empire and it was not until the early Modern period that the first signs of revival can be detected.
In 1634, four years after his death, a work by the renowned astronomer Johannes Kepler was published. The work was entitled "Somnium", meaning "Dream." It tells of a man who is transported to the Moon by magical means and describes what he found there. Although the means of transportation was unrealistic, Kepler went on to describe the Lunar environment in terms consistent with the scientific knowledge of the time; explaining how day and night are much longer than on Earth and how, therefore, there would be great differences in temperature. He also describes how Earth would be a much bigger disc in the Lunar sky and would be visible from only one hemisphere of the Moon. There is life on the Moon: it springs from the soil and lives only for a Lunar day.
Kepler was also one of the first to put forward the "Hollow Earth" theory in which our planet is composed of a series of nested spheres.
