For the worlds oldest objects, uranium-thorium-lead dating is the most useful method. We use it to date the Earth, Higham said. While radiocarbon dating is useful only for materials that were once alive, scientists can use uranium-thorium-lead dating to measure the age of objects such as rocks.

How do we know earth is 4.5 billion years old?

By dating the rocks in Earths ever-changing crust, as well as the rocks in Earths neighbors, such as the moon and visiting meteorites, scientists have calculated that Earth is 4.54 billion years old, with an error range of 50 million years.