Spherical Earth
The concept of a spherical Earth suggests that our planet is shaped like a sphere, rather than flat. This idea has been supported by various observations, such as the way ships disappear hull-first over the horizon and the round shadow Earth casts on the Moon during a lunar eclipse.
Scientific evidence, including images from space and the way gravity pulls objects toward the center, further confirms this shape. The Earth's rotation also contributes to a slight bulging at the equator, making it an oblate spheroid rather than a perfect sphere.