Earth and the Moon are 60 Million Years Older Than Previously Thought

It turns out that the Earth's moon may be far older than once thought. Scientists have discovered that the timing of the massive impact between our planet and a planet-sized body, named Theia, occurred around 40 million years after the start of the solar system. That means that the final stage of Earth's formation is about 60 million years older than previously thought.

Looking back millions and billions of years is difficult. In order to see back into "deep time," the scientists needed to take a look at an isotopic signal. More specifically, the researchers analyzed xenon gas found in South African and Australian quartz, which had been dated to 3.4 and 2.7 billion years. The gas served as a time capsule that allowed the researchers to compared current isotopic ratios of xenon to those that 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," said Guillaume Avice, one of the researchers, in a news release. "That 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 give us new data and allow us to refine the measurement."

In fact, the xenon gas allowed the researchers to calculate when the atmosphere was being formed, which was probably at the same time that our planet collided with a planet-sized body which created the moon. In the end, the scientists found that the moon-forming impact was about 60 million years older than previously thought.

"This might seem like a small difference, but it is important," said Bernard Marty, one of the researchers, in a news release. "These differences set time boundaries on how the planets evolved, especially through the major collisions in deep time which shaped the solar system."

The findings were presented at the Goldschmidt Geochemistry Conference in California.