Imbrium Sculpture (IMAGE) Brown University Caption Grooves and gashes associated with the Imbrium Basin on the moon have long been puzzling. New research shows how some of these features were formed and uses them to estimate the size of the Imbrium impactor. The study suggests it was big enough to be considered a protoplanet. Credit NASA/Northeast Planetary Data Center/Brown University 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.