What is the age of the earth and how do we know this?

Calculations of the half life of uranium, which is approximately 4.5 billion years, are the main source of information used to determine the age of the earth. Samples of uranium that are half lead, the daughter element, and half uranium show that one half life of uranium has passed.

These calculations are predicated on the following assumptions: that all of the original uranium was 100% uranium; that there was no lead present during the mineral's formation; and that no uranium has been lost to erosion during the mineral's estimated 4.5 billion years of existence.

Naturally, there is room for error in the assumptions of 100% uranium and no erosion, but 4.5 billion years is the estimated age of the earth based on these calculations.

The age of the Earth is approximately 4.54 billion years. Scientists determine this age using various methods, including radiometric dating of rocks and minerals, analysis of meteorites, and studying the decay rates of radioactive isotopes.