The half-life is the amount of time it takes for one half of the initial amount of the parent, radioactive isotope, to decay to the daughter isotope.
Thus, if we start out with 1 gram of the parent isotope, after the passage of 1 half-life there will be 0.5 gram of the parent isotope left.
However, rocks and other objects in nature do not give off such obvious clues about how long they have been around.
So, we rely on radiometric dating to calculate their ages.
Relative dating is used to determine a fossils approximate age by comparing it to similar rocks and fossils of known ages.
Absolute dating is used to determine a precise age of a fossil by using radiometric dating to measure the decay of isotopes, either within the fossil or more often the rocks associated with it.
Mikhail Marov of the Vernadsky Institute of Geochemistry and Analytical Chemistry said scientists had determined the meteorite's age by observing the amount of radioactive isotopes and their decay byproducts, a technique called of a granodiorite at the Cuttaburra A prospect indicates that this mineralised system may be Middle Silurian in age and thus indicating that the host rocks are older than those hosting the Cobar-type deposits.
A method for determining the age of an object based on the concentration of a particular radioactive isotope contained within it.
Radiometric dating, or radioactive dating as it is sometimes called, is a method used to date rocks and other objects based on the known decay rate of radioactive isotopes.
Different methods of radiometric dating can be used to estimate the age of a variety of natural and even man-made materials.
Geologists have a much harder job keeping track of time.
Studying the Earth and its evolution, they work with time scales of thousands to billions of years.