Most people are aware that Earth, the moon, the Sun and basically everything in outer space is really old. So old, in fact, that trying to precisely determine the age of celestial entities is hardly worth the bother. That hasn’t stopped geochemists from the University of Lorraine in Nancy, France from trying, and their latest findings suggest that the timing of the giant impact between Earth’s ancestor and a planet-sized body occurred around 40 million years after the start of solar system formation. That would make Earth and it’s resulting spinoff (the moon) about 60 million years older than previously believed.

“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 my,” said geochemist Guillaume Avice.

What Avice and his colleagues found is an isotopic signal that suggests earlier age estimates for the Earth and moon are likely a little on the low side. Precise age estimates reaching so far back can be difficult, because geologists don’t have any of their normal indicators (e.g., rock layers) to rely on. What they did instead was analyze xenon gas found in South African and Australian quartz, which had been dated to 3.4 and 2.7 billion years respectively. Because the gas is effectively sealed and preserved within the rock, the researchers were able to compare the current isotopic ratios of xenon with those which existed billions of years ago.

“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,” said Avice.

For having just had an extra 60 million years tacked onto their age, both the Earth and moon are looking pretty good.