The Hollow Earth Hypothesis says that the planet Earth is hollow and powered by an interior sun 1000 km (600 miles) across that provides light to an advanced inner-Earth civilization or maybe prehistoric creatures. Openings to the inner earth are thought to be in either poles, but can also be in other places around the world like Peru, Tibet, or Mount Shasta, in California. The Nazi era Thule Society spoke a lot about Tibetan myths of openings into the Earth. There is even a theory that Hitler ordered a research journey for such an opening in Antarctica. During the Nuremberg Trials, Admiral Dönitz spoke of "an invisible fortification, in midst of the eternal ice." perhaps the real location where Hitler fled? Some believe UFOs actually come from within the Earth, maybe piloted by descendants of Atlantians. The Hollow Earth hypothesis has long been contradicted by overwhelming observational Evidence, as well as by the modern understanding of planet formation but the possibility is still out there.