Geochemists from the University of Lorraine in Nancy, France have analysed xenon gas found in South African and Australian quartz, which had been dated to 3.4 and 2.7 billion years respectively. The gas sealed in this quartz is preserved as in a "time capsule," allowing researchers to compare the current isotopic ratios of xenon, with those which existed billions of years ago. Recalibrating dating techniques using the ancient gas allowed them to refine the estimate of when the Earth began to form. This allows them to calculate that the Moon-forming impact is around 60 million years (+/- 20 m. y.) older than previously thought.