Radiometric dating process
When an isotope decays, it often becomes a different kind of element altogether.
Because this new element (decay product) remains on or within the object, scientists can easily determine how old the object is. A mass spectrometer is a fundamental device in any radiometric dating experiment.
Using fossils as guides, they began to piece together a crude history of Earth, but it was an imperfect history.
After all, the ever-changing Earth rarely left a complete geological record.
Measuring the uranium-to-lead ratios in the oldest rocks on Earth gave scientists an estimated age of the planet of 4.6 billion years.
However, samples must be taken from several different areas of the object being studied to ensure maximum accuracy.Scientists discovered that rocks could be timepieces -- literally.Many chemical elements in rock exist in a number of slightly different forms, known as isotopes.Certain isotopes are unstable and undergo a process of radioactive decay, slowly and steadily transforming, molecule by molecule, into a different isotope.This rate of decay is constant for a given isotope, and the time it takes for one-half of a particular isotope to decay is its radioactive half-life.