How do we know the age of things?

What is Carbon Dating and how does it work?

Some atoms have an unusual amount of protons and neutrons in them – we call these unusual atoms “isotopes” – Isotopes are commonly found in many things, but they don’t last forever. Over time these isotopes lose their protons and neutrons at a steady rate until they resemble a normal atom.

So by counting the number of isotopes there are, we can work out how old something is.

The first element we used for this method of dating was Carbon. After being formed, Carbon will lose half of all its isotopes 5,730 years later – and in 11,460 years time that same lump of Carbon will now only have a quarter of its original isotopes. If you hear anyone mention “half life” this is the rate at which an isotope becomes a normal atom.

Carbon has a relatively short half life, meaning it is very accurate for aging things that have been made during human civilization. But how do we then date something older?

We use different elements. The principle is exactly the same, but we use something other than Carbon – for instance Beryllium has a half life of 1.52 million years and Potassium has half life of 1.26 billion years. Every type of atom can have its own isotope, and every isotope has its own half life.

Regardless of what element is used, the term “Carbon Dating” is still often used as this is the term the people are most familiar with.

Carbon dating and similar methods has been proven to be accurate time and again. if you would like to learn more, have a read at this:…/how-do-geologists-use-carbon…/

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DeafDave is a Deaf person who uses Auslan (Australian Sign Language). He is from Australia.
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