Image Credit & Copyright: Bob and Janice Fera (Fera Photography)
Explanation: This helmet-shaped cosmic cloud with wing-like appendages
is popularly called Thor's Helmet. Heroically sized even for a Norse god, Thor's Helmet
is about 30 light-years across. In fact, the helmet is more like an interstellar bubble, blown as a fast wind from the
bright, massive star near the bubble's center sweeps through a surrounding
molecular cloud. Known as a Wolf-Rayet
star, the central star is an extremely hot giant thought to be in a brief,
pre-supernova stage of evolution. Cataloged as NGC
2359, the nebula is located about 15,000 light-years
away in the constellation Canis Major. The
sharp image, made
using broadband and narrowband filters, captures striking details of the nebula's
filamentary structures. It shows off a blue-green color from strong emission due
to oxygen atoms in the glowing gas.
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