age of the Earth

Modern geologists consider the age of the Earth to be around 4.54 billion years (4.54×109 years).[1] This age represents a compromise between the interpretations of oldest-known terrestrial minerals – small crystals of zircon from the Jack Hills of Western Australia – and astronomers' and planetologists' determinations of the age of the solar system based in part on radiometric age dating of meteorite material and lunar samples.

Interpretation of radiometric age dating of zircons suggests that the Earth is at least 4.404 billion years old. Comparing the mass and luminosity of the Sun to the multitudes of other stars, it appears that the solar system cannot be much older than those rocks. Ca-Al-rich inclusions (inclusions rich in calcium and aluminium) – the oldest known solid constituents within meteorites which are formed within the solar system – are 4.567 billion years old, giving an age for the solar system and an upper limit for the age of the Earth. It is assumed that the accretion of the Earth began soon after the formation of the Ca-Al-rich inclusions and the meteorites. Because the exact accretion time of the Earth is not yet known, and the predictions from different accretion models vary from several millions up to about 100 million years, the exact age of the Earth is difficult to determine.