... Sometimes it's hard to believe what you see in the sky. During the Shelios Expedition to Greenland in late August, even veteran sky enthusiasts saw auroras so colorful, so fast changing, and so unusual in form that they could remember nothing like it. An Ancient Stream Bank on Mars . ... A Galaxy Collision in NGC 6745 . ... NGC 7023: The Iris Nebula . ... Sometimes called the Iris Nebula and dutifully cataloged as NGC 7023 this is not the only nebula in the sky to evoke the imagery of flowers. ...