New research suggests an ancient impact between Earth and a larger object that formed the moon occurred about 40 million years after the birth of the solar system; this means the final stage of the Earth's formation is 60-million years older than previously believed.
Researchers looked at an isotopic signal that indicates the age of the Earth in its final phase and the moon have been underestimated, a European Association of Geochemistry news release reported.
Looking into "deep time" is tricky because in the early stages of Earth's formation there was not "classic geology" such as rock layers.
In order to study this mysterious time researchers look at the proportions of different gases, dubbed isotopes, which are leftover from those early days.
A researchers looked at xenon gas in South African and Australian quartz that is believed to be between 2.7 and 3.4 billion years old. This gas allowed them to calculate that the ancient impact is about 60 million years older than preciously thought.
In the past it was believed the Earth's atmosphere dated to 100 million years after the formation of the solar system; since the atmosphere could not have survived that kind of impact it must be older than this estimate.
"It is not possible to give an exact date for the formation of the Earth. What this work does is to show that the Earth is older than we thought, by around 60 [million years]," Guillaume Avice said in the news release.
"The composition of the gases we are looking at changes according the conditions they are found in, which of course depend on the major events in Earth's history. The gas sealed in these quartz samples has been handed down to us in a sort of 'time capsule'. We are using standard methods to compute the age of the Earth, but having access to these ancient samples gives us new data, and allows us to refine the measurement," he said.
