Before revision: upright=1.4|A cross-sectional drawing of the planet Earth showing the "Interior World" of Atvatabar, from William R. Bradshaw's 1892 science-fiction novel The Goddess of Atvatabar The Hollow Earth is a concept proposing that the planet Earth is entirely hollow or contains a substantial interior space.
After revision: hypotheticalupright=1.4|A cross-sectional drawing of the planet Earth showing the "Interior World" of Atvatabar, from William R. Bradshaw's 1892 science-fiction novel The Goddess of Atvatabar The Hollow Earth is a concept proposing that the planet Earth is entirely hollow or contains a substantial interior space.