Geologists have calculated the age of Earth at 4.6 billion years. But for humans whose life span rarely reaches more than 100 years, how can we be so sure of that ancient date? It turns out the ...

In 1911 the discovery that the world was billions of years old changed our view of the world for ever. Imagine trying to understand history without any dates. You know, for example, that the First ...

In 1902 Ernest Rutherford and Frederick Soddy discovered that radioactive elements, such as uranium and thorium, broke down into other elements in a predictable sequence or series. This amazing fact ...