Perhaps the most famous absolute dating technique, radiocarbon dating was developed during the 1940s and relies on chemistry to determine the ages of objects. Used on organic matter, the technique measures the amount of radioactive carbon decay to determine an objects age.

How can you tell how old something is?

So how do scientists do it? Radiocarbon dating is the most common method by far, according to experts. This method involves measuring quantities of carbon-14, a radioactive carbon isotope — or version of an atom with a different number of neutrons. Carbon-14 is ubiquitous in the environment.

What two methods are used to determine the age of a rock or fossil?

​There are two main ways to determine the age of a rock, these are Relative dating and Absolute dating. Relative dating is used to determine the relative order of past events by comparing the age of one object to another.

How do we know how old the dinosaurs are?

There are two ways to determine the age of a dinosaur fossil. One is called relative geologic time, which involves deciding whether one dinosaur fossil is older or younger than another. The other is often called absolute geologic time, which involves estimating how many millions of years old a dinosaur fossil is.