The oldest meteorites ever dated in the Solar System are 4,56 billion years old, the oldest minerals on Earth are 4,4 billion years old, and the oldest rocks on Earth are 4 billion years old.
These ages are very consistent because the meteorites had to form before the accretion of our planet, and the Earth had to cool down before the first minerals could crystallise.
Studies of strata, the layering of rocks and earth, gave naturalists an appreciation that Earth may have been through many changes during its existence.These layers often contained fossilized remains of unknown creatures, leading some to interpret a progression of organisms from layer to layer.Because the exact amount of time this accretion process took is not yet known, and the predictions from different accretion models range from a few million up to about 100 million years, the exact age of Earth is difficult to determine.It is also difficult to determine the exact age of the oldest rocks on Earth, exposed at the surface, as they are aggregates of minerals of possibly different ages.Additionally, elements may exist in different isotopes, with each isotope of an element differing in the number of neutrons in the nucleus.
Meteorites are among the oldest objects we know about - formed about 4.5 billion years ago. This article describes the principles and methods used to make that determination.
he generally accepted age for the Earth and the rest of the solar system is about 4.55 billion years (plus or minus about 1%).
This value is derived from several different lines of evidence.
Calcium-aluminium-rich inclusions—the oldest known solid constituents within meteorites that 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 Earth.
It is hypothesised that the accretion of Earth began soon after the formation of the calcium-aluminium-rich inclusions and the meteorites.
The method compares the abundance of a naturally occurring radioactive isotope within the material to the abundance of its decay products, which form at a known constant rate of decay.