Deep within Earth’s mantle lie two enormous regions, often referred to as "islands," which are the size of continents.

Scientists may finally be closing in on the origins of two colossal, mysterious structures buried nearly 1,800 miles inside Earth—hidden formations that have puzzled researchers for decades. New ...

What Earth do you live on? A round one? Flat one? Maybe your world is resting on the back of a huge cosmic turtle? What about a hollow Earth? Just a planet’s shell levitating around absolutely nothing ...