Okay so I understand at a very basic level how radiometric dating works, but I have a question. How do scientists know the half-life of isotopes, when some of them are measured in millions or billions ...

Despite seeming like a relatively stable place, the Earth's surface has changed dramatically over the past 4.6 billion years. Mountains have been built and eroded, continents and oceans have moved ...

we know we can touch rocks that are 1.7 billion years old.

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 ...

On the Atlantic coast of the U.S., archaeologists found oyster shells left by Native Americans more than 4,000 years ago. In Morocco, paleontologists excavated the fossils of a dinosaur that roamed ...