Carbon 14 is continually being created in the Earth's atmosphere by the interaction of nitrogen and gamma rays from outer space.Since atmospheric carbon 14 arises at about the same rate that the atom decays, the Earth's levels of carbon 14 have remained constant.As we mentioned above, the carbon-14 to carbon-12 ratio in the atmosphere remains nearly constant.

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So by measuring carbon 14 levels in an organism that died long ago, researchers can figure out when it died.

The procedure of radiocarbon dating can be used for remains that are up to 50,000 years old.

Radiocarbon dating uses isotopes of the element carbon. Cosmic rays – high energy particles from beyond the solar system – bombard Earth’s upper atmosphere continually, in the process creating the unstable carbon-14. Because it’s unstable, carbon-14 will eventually decay back to carbon-12 isotopes.

Because the cosmic ray bombardment is fairly constant, there’s a near-constant level of carbon-14 to carbon-12 ratio in Earth’s atmosphere.

Follow the links below to learn more about radiocarbon dating. Radiocarbon dating uses carbon isotopes A special kind of radiocarbon dating: Bomb radiocarbon dating What is an isotope?

To understand radiocarbon dating, you first have to understand the word Although an element’s number of protons cannot change, the number of neutrons can vary slightly from each atom.

A form of radiometric dating used to determine the age of organic remains in ancient objects, such as archaeological specimens, on the basis of the half-life of carbon-14 and a comparison between the ratio of carbon-12 to carbon-14 in a sample of the remains to the known ratio in living organisms. A technique for measuring the age of organic remains based on the rate of decay of carbon 14.

The carbon 14 present in an organism at the time of its death decays at a steady rate, and so the age of the remains can be calculated from the amount of carbon 14 that is left. The cells of all living things contain carbon atoms that they take in from their environment.

In The Cosmic Story of Carbon-14 Ethan Siegel writes: The only major fluctuation [in carbon-14] we know of occurred when we began detonating nuclear weapons in the open air, back in the mid-20th Century.