What is radioactive carbon dating
Here on Earth, Carbon is found in the atmosphere, the soil, the oceans, and in every living creature. C-12, so-named because it has an atomic weight of 12 – is the most common isotope, but it is by no means the only one.Carbon 14 is another, an isotope of carbon that is produced when Nitrogen (N-14) is bombarded by cosmic radiation.A detailed description of radiocarbon dating is available at the Wikipedia radiocarbon dating web page.Bottom line: Radiocarbon dating is a technique used by scientists to learn the ages of biological specimens from the distant past.On the other hand, atmospheric testing of nuclear weapons during the 1950s and 1960s is likely to have increased the Carbon 14 content of the atmosphere.In fact, research has been conducted which suggests that nuclear tests may have doubled the concentration of C-14 in this time, compared to natural production by cosmic rays. If you’d like more info on Carbon Dating, check out NASA’s Virtual Dating: Isochron and Radiocarbon – Geology Labs On-line, and here’s a link to USGS Radiometric Dating Page.
It can be used on objects as old as about 62,000 years. Atoms of the same element that have different numbers of neutrons are called isotopes. Most carbon on Earth exists as the very stable isotope carbon-12, with a very small amount as carbon-13.It’s not absolutely constant due to several variables that affect the levels of cosmic rays reaching the atmosphere, such as the fluctuating strength of the Earth’s magnetic field, solar cycles that influence the amount of cosmic rays entering the solar system, climatic changes and human activities.Among the significant events that caused a temporary but significant spike in the atmospheric carbon-14 to carbon-12 ratio were above-ground nuclear test detonations in the two decades following World War II.The unstable carbon-14 gradually decays to carbon-12 at a steady rate. Scientists measure the ratio of carbon isotopes to be able to estimate how far back in time a biological sample was active or alive.This plot shows the level of carbon-14 in the atmosphere as measured in New Zealand (red) and Austria (green), representing the Southern and Northern Hemispheres, respectively.