According to most scientists studying the Earth's geological past, our planet is approximately 4.5 billion years old. However, this is not a completely accurate measurement, as the margin of error for this dating is estimated at 10%. Several times before, the Earth's age was recalculated as new evidence was found and techniques improved. What was seen is that, with each measurement taken, the Earth was older than imagined.
The method used to calculate the age of the Earth is the dating of Uranium atoms, which transform into lead atoms, releasing radiation. With that, after a certain time, which is called half-life, only half of this uranium remains. Thus, by calculating the amount of uranium remaining in the oldest rocks on the planet, it is possible to specify its age.
It is interesting to note that this dating is not carried out on rock formations originating from the Earth itself, but on fragments of meteorites that have fallen on our planet. This is because the Earth's rocks are constantly changing, through the rock cycle, which makes it difficult to accurately measure their ages.
According to this measurement and considering the successive periods that marked the geological ages, we can consider that the history of mankind is very small compared to the history of Earth. For this reason, it is customary to distinguish the historical time of geological time. The first is always measured on the scale of thousands, and the second on the scale of millions and billions.
To get an idea of this difference, if we reduce the Earth's history to 24 hours, the first homo sapiens would have appeared at 23 hours, 59 minutes and 57 seconds. The man's story, therefore, would be a mere 3 seconds.
By Rodolfo Alves Pena
Graduated in Geography
Source: Brazil School - https://brasilescola.uol.com.br/geografia/qual-idade-terra.htm
