Lunar Impact (IMAGE) Southwest Research Institute Caption This image shows an artist’s depiction of what a large lunar impact event might look like well after the end of lunar impact basin formation, where a basin is defined as a 300-km (186-mile) diameter or larger crater. Several enormous basins can be seen in the upper right portion of the Moon. They were filled in by dark lava well after they formed. Many basins formed between 3.7–4.1 billion years ago during the so-called Late Heavy Bombardment of the Moon. Credit Art by Don Davis Usage Restrictions May be used by media and the public for educational and informational purposes 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.