The presence of two types of hair cells, the inner and outer hair cells ... to finding that light comes out of the eye (which has never been observed). Within five years it was discovered that the ...

Above the inner core is the outer core, a shell of liquid iron. This layer is cooler but still very hot, perhaps 7,200 to 9,000 degrees Fahrenheit (4,000 to 5,000 degrees Celsius). It too is ...