Micrometeorite (IMAGE) Penn State Caption Iron micrometeorites, like seen here under a microscope, can provide new clues about the composition of the Earth's upper atmosphere 2.7 billion years ago. Credit Andrew Tomkins Usage Restrictions non commercial use only 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.