Gravitational lensing (IMAGE) University of Toronto Caption Gravitational lensing in action. This phenomenon is used by astronomers to study very distant and very faint galaxies. Credit NASA, ESA & L. Calçada Usage Restrictions ESA/Hubble images, videos and web texts are released under the Creative Commons Attribution 4.0 International license and may on a non-exclusive basis be reproduced without fee provided they are clearly and visibly credited. 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.