Darren Williams, a professor of astronomy (IMAGE) Penn State Caption New research by Darren Williams, a professor of astronomy and astrophysics at Penn State Behrend, pictured here, and Michael Zugger, a senior research engineer at the Applied Research Lab at Penn State, offers a new possibility for how the moon formed: a binary-exchange capture as two objects passed near a much-younger Earth. Credit Penn State Behrend Usage Restrictions Credit must be given to the creator. Only noncommercial uses of the work are permitted. No derivatives or adaptations of the work are permitted. License CC BY-NC-ND 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.