... Inside the Eagle Nebula . ... A closer look at the Eagle Nebula, however, shows the bright region is actually a window into the center of a larger dark shell of dust. ... NGC 2359: Thor s Helmet . ... Heroically sized even for a Norse god, Thor's Helmet is about 30 light-years across. ... Sprawling across almost 200 light-years, emission nebula IC 1805 is a mix of glowing interstellar gas and dark dust clouds about 7,500 light-years away in the Perseus spiral arm of our galaxy. ...