Thor s Helmet in H Alpha . ... Credit Copyright: Don Goldman Explanation: Near picture center, the helmet-shaped structure with wing-like appendages is popularly called Thor's Helmet . Cataloged as NGC 2359, the striking nebula is located about 15,000 light-years away in the constellation Canis Major . The helmet is actually more like a cosmic bubble , blown as the wind from the bright, massive star near the bubble's center sweeps through the surrounding molecular cloud. ...