It seems really farfetched to me, are we counting fossil rings or something?
In: Chemistry
One of the most well-known methods is radiocarbon dating.
As you might know, all things are made up of atoms. At the center of every atom is something called a nucleus, which is made up of protons and neutrons. The exact number of protons and neutrons tells you what kind of atom it is.
Not all nuclei are created equal. Some of them are unstable, which means that when they’re formed, they start decaying, which changes the number of protons an neutrons in the nucleus.
Carbon-14 is one of these types of unstable elements. C-14 is constantly being created when high-speed particles in space collide with atoms in our atmosphere. Since C-14 is unstable, it starts to decay as soon as it’s created.
C-14 is everywhere, and plants constantly absorb it when they absorb carbon dioxide. Then, it gets into animals when they eat the plants.
When a plant or animal is alive, they’re constantly absorbing new C-14. But when they die, they stop.
Scientists can analyze a sample and check how much C-14 is in it. In a very old sample, a lot of the C-14 will have decayed. A newer sample will have more of it.
>are we counting fossil rings or something?
You can actually do something very similar to that with layers of earth. Just like trees add rings, new layers of rock are constantly being formed and buried. By determining which layer of rock you find a fossil in, you can make assumptions about its age.
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