This document discusses how scientists use absolute dating to determine the exact age of rocks and fossils. It explains that atoms naturally decay over time, changing from a parent atom to a daughter atom. By measuring the ratio of parent to daughter atoms in a sample, and knowing the half-life of the parent atom, scientists can calculate how many half-life periods have passed and determine the precise numerical age of the object. The document provides an example using a parent atom with a 10,000 year half-life and concludes that scientists have used absolute dating methods to determine that Earth is approximately 4.6 billion years old.

1. Absolute Dating Chapter 8, Section 3

2. Think About It . . . How old is Earth? What are some tools or methods that scientists could use to figure out the age of Earth?