Above is a photo of the oldest fragment of Earth ever found, which is called a zircon 4. The zircon 4 is 4.375 billion years old and may have implications of our understanding of the formation of planet Earth.
John Valley of the University of Wisconsin-Madison used a technique called atom-probe tomography. This technique lets scientists count individual lead atoms within the zircons.
The fragment was found in Jack Hills in Western Australia. Based on research from scientists, it was determined that the zircons were formed only 100 million years after the cosmic impact that smashed the Earth to create the Moon.