Crescent Nebula and Soap Bubble
The Crescent Nebula is an emission nebula in the constellation Cygnus, about 5000 light-years away from Earth. This is a 7.7 hour exposure in OIII and HA. If you look carefully lower left you can see the 'soap bubble' which was only discovered in 2007 by an amateur astronomer. Starless version shows gas structures.
7.7 hour exposure
230 x 120"
OIII & HA filters