1
Cosmic rays batter the upper atmosphere and send cascades of neutrons through the air
Neutrons
Nitrogen
2
These strike atoms of nitrogen, the main component of Earth’s atmosphere, and transform some of them into carbon-14
Two extra
neutrons
Carbon-14
Has six protons and eight neutrons in its nucleus, which makes it unstable, so that it decays radioactively into an atom of nitrogen. Most of the carbon in our bodies and the world has six protons and six neutrons
3
Carbon-14 atoms combine with oxygen to create radioactive carbon dioxide that is absorbed by plants, which are then eaten by animals
4
When an organism dies, it stops absorbing carbon-14 and its existing store slowly decays
5
By measuring its radioactivity, its carbon-14 content can be estimated and the date of its time of death can be measured
1
Cosmic rays batter the upper atmosphere and send cascades of neutrons through the air
Carbon-14
Has six protons and eight neutrons in its nucleus, which makes it unstable, so that it decays radioactively into an atom of nitrogen. Most of the carbon in our bodies and the world has six protons and six neutrons
Neutrons
Nitrogen
Two extra
neutrons
2
These strike atoms of nitrogen, the main component of Earth’s atmosphere, and transform some of them into carbon-14
3
Carbon-14 atoms combine with oxygen to create radioactive carbon dioxide that is absorbed by plants, which are then eaten by animals
4
When an organism dies, it stops absorbing carbon-14 and its existing store slowly decays
5
By measuring its radioactivity, its carbon-14 content can be estimated and the date of its time of death can be measured