Like its relative, the Blue Racquetball, the Blue Snowball also shows off its blue-green glow due to the color of ionized oxygen. Here you can see the outer shell of gas expended by the dying star (not visible) in the center. 15" F/5 Dobsonian, 5mm LVW eyepiece (380x). Mount Tamalpais State Park, CA. 2008-09-27.