Hollow earth ! I say yes ! How about you? .
Edmund Halley was a brilliant English astronomer whose mathematical calculations pinpointed the return of the comet that bears his name. Halley was fascinated by the earth's magnetic field. He noticed the direction of the field varied slightly over time and the only way he could account for this was there existed not one, but several, magnetic fields. Halley came to believe that the Earth was hollow and within it was a second sphere with another field. In fact, to account for all the variations in the field, Halley finally proposed that the Earth was composed of some four spheres, each nestled inside another.
Halley also suggested that the interior of the Earth was populated with life and lit by a luminous atmosphere. He thought the aurora borealis, or northern lights, was caused by the escape of this gas through a thin crust at the poles.
Others picked up Halley's hollow-earth theory often adding their own twists. In the eighteen century Leonhard Euler, a Swiss mathematician, replaced the multiple spheres theory with a single hollow sphere which contained a sun 600 miles wide that provided heat and light for an advanced civilization that lived there. Later Scottish mathematician Sir John Leslie proposed there were two inside suns (which he named Pluto and Proserpine).