Hollow Earth is a belief that the planet Earth has a hollow interior and, possibly, a habitable inner surface. The hypothesis of a Hollow Earth has long been contradicted by overwhelming evidence as well as by the modern understanding of planet formation, and the scientific community now dismisses the notion as pseudoscience.
The deepest hole drilled to date is the SG-3 borehole which is 40,230 feet (7.6m/12/3 km) deep, part of the Kola Superdeep Borehole project, and thus visual knowledge of the Earth's structure extends that far.
hollow earth, unexplained truth, alien, earth, planet x