Thor's Helmet is created by the brightest star inside the "bubble". This star
is a rare Wolf-Raynet star, a massive, hot blue giant whose high velocity solar
wind slams into the surrounding interstellar gas and dust and creates the intricate
patterns in this nebula. For another example of a bubble blown by a Wolf-Raynet star,
see the image of the "Bubble Nebula". Thor's Helmet is in the constellation Canis
Major. The main bubble is about 30 light years across, and it is 1500 light years
from earth.

This image won the January 2008 Digital Astrophotography Group
"Moderator Challenge" photo contest.
It was also printed on page 86 of the June, 2008 issue of "Sky and Telescope".



Image data:
Camera: Canon 350 XT (modified)
Exposure: ISO 800, 5 minutes x 12
Telescope: 10" Schmidt-Newtonian, Baader coma corrector