Neptune-like exoplanet (IMAGE) University of Kansas Caption An artist's concept of the exoplanet GJ 9827d, the smallest exoplanet where water vapor has been detected in the atmosphere. Credit NASA/ESA/Leah Hustak, Ralf Crawford, Space Telescope Science Institute 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.