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 actually 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.
