Shining Noctilucent Clouds (IMAGE) NASA/Goddard Space Flight Center Caption NASA's Aeronomy In the Mesosphere mission captures images like this of shining noctilucent clouds, also known as polar mesospheric clouds, which hover over Earth's poles in summertime. Credit Credit: NASA/AIM 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.