Jupiter Europa and Io (IMAGE) Southwest Research Institute Caption SwRI scientists used Hubble Space Telescope to image the surface of Jupiter’s fourth largest moon Europa (shown lower right in this composite image) in the ultraviolet, mapping concentrations of sulfur dioxide on its surface that likely came from Io (above), Jupiter’s ultra-volcanic moon. Credit NASA Usage Restrictions No restrictions. License Public Domain 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.