Deep Sky

Bubble Nebula
Constellation: Cassiopeia

This has got to be one of the coolest nebulas around.  Needless to say, its pretty obvious how it got its name.  It is an emission nebula not too far away from M52.  The 'bubble' is created by the stellarwind from a 8.7 mag. young central very hot star.  This dude has the very sexy name of  SAO20575or if you really want to get up closeand personal BD+602522. (Thought to have a mass of 10 to 40times our sun.)
We've got two things here: 
1. the molecular cloud
2. bubble nebula expanding (as we speek)

Discovered William Herschel in 1787.