2.2 APOD

This picture was taken during a sunset in Sweden. Because sunset rises up, it often appears to be night on the ground and day in the air. This picture is a little different, however, because of the Noctilucent clouds seen in the sky. These Noctilucent clouds, also known as polar mesopheric clouds, are the highest clouds in the Earth's atmosphere. They are often visible in the summer months at places of high latitudes, like Sweden. Not much is known about these clouds, ut it is thought that they are made up of ice particles. Several satellites have been launched to study the objects. Scientists have found clouds similar to the Noctilucent clouds made of carbon dioxide on Mars.