In comparison to human life, the Earth is incredibly old. Throughout history, and with technological developments that enable more precise measurements, we have been able to determine the age of the Earth with a lot of precision.
The associated difficulties
Even if at a first it might seem that measuring the age of the Earth is an easy task, it is not at all. Indeed, there isn’t enough with taking a rock and looking at when it was formed: the Earth is a very dynamic planet, with volcanic eruptions and tectonic plate movements that constantly recycle old rocks with new ones.
Moreover, other processes that could help us to estimate the age of the Earth are also processes that aren’t constant throughout time, and that, therefore are not useful for us.
A solution to this problem
As we can’t find the primordial rocks on our planet, scientists had to find alternative solutions, such as measuring the age of celestial bodies without geological activity.
For example, the lunar rocks that brought the astronauts during the Apollo missions show a bigger age than the rocks found on Earth. However, even if nowadays the Moon is a body with very little geological activity, it has not always been the case. Many scientists affirm that the Moon had been very active in its early history.
Even if the Moon’s rocks present much older ages than the rocks on Earth, they aren’t primordial. It is for this reason that surged the idea of measuring the age of the meteorites. As it is accepted that all the bodies that form the solar system were formed at the same time, this means that a meteorite will have the same age as our planet.
A definitive age
Thanks to the measure of the age of meteorites that impacted the Earth, we nowadays know that the Earth has an approximate age of 4.6 billion years, like all the other bodies in the solar system.
Even if I have commented that the rocks on Earth constantly regenerate, rocks in North-West Canada have been found dating from 4.03 billion years. Moreover, the analysed lunar rocks show an age of 4.4 billion years. Together with the antiquity found on meteorites, this confirms that the Earth has an approximate age of 4.6 billion years.