Thor’s Helmut, NGC 2359

 Thor’s Helmut, NGC 2359 This helmet-shaped cosmic cloud  is popularly called Thor’s Helmet. Heroically sized even for a Norse god, Thor’s Helmet spans about 30 light-years across. In fact, the helmet is more like an interstellar bubble where the solar wind from bright star near the center of the bubble’s blue-hued region sweeps through the surrounding molecular cloud and expands the gas. This star, a Wolf-Rayet, is a massive and extremely hot giant star thought to be in a brief, pre-supernova stage of evolution. Cataloged as NGC 2359, the emission nebula is located about 12,000 light years away toward the constellation of the Big Dog (Canis Major). The image, made using  narrowband filters, captures striking details of the nebula’s filamentary gas and dust structures. Hydrogen is red in the image and the blue green color originates from strong emission from oxygen atoms in the nebula. Most narrowband images are done in the Hubbell palette where Hydrogen is green. However in this image I have made Hydrogen as red and Oxygen as blue green which makes the image almost true color since these are the colors of Hydrogen and Oxygen gas emission.