Timeline (IMAGE) University of Wisconsin-Madison Caption This is a timeline of the history of our planet places the formation of the Jack Hills zircon and a "cool early Earth" at 4.4 billion years. Credit Andree Valley Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.