This session is centered on the Bubble Nebula - NGC7635, a nebula at the edge of the constellation Cassiopeia, near Cephus. It's a popular patch of the celestial sphere, and the frame include 2 open clusters and another, less dramatic nebula.

A hot young star was born in a molecular cloud of molecular hydrogen, and it's stellar winds set about pushing the gas cloud away. The gas cloud pushed back, and the result is a slightly denser shell of material around the star. Starlight from other stars in the neighbourhood diffract off the shell like sunlight off a pond, and we end up with something that looks like a soap bubble.

The bubble nebula is between 7100 and 11 thousand light years away. Nearby, as the eyes sees, is the nebula NGC7538, a more confidant 9100 light years. This is another star birthing ground, and this one claims the largest proto star yet discovered - a star about 300 times the size of out sun.

The two open clusters in the frame, M52 and NGC7510 are also of interest.

As is my habit now, I've combine frames from a similar session last year with new frames taken a few days ago.