NGC 7000: North America Nebula
NGC 7000 is a emission nebula into the constellation of Swan, located near of Deneb star. Because your shape also has the name of North America Nebula, as the dark central area is named Gulf of Mexico too.
Is a interstellar cloud of ionized hidrogen that fill an angular area similar to full moon, but its low shallow brightness do that normally don't be visible at naked eye. The dark central area is a very dense region of interstellar matter located in front of nebula wich soak up light of it, giving to body its caracteristic shape. Is believed that Deneb is who cause its light emission (toward upper right out of image), this could mean that distance to NGC 7000 is 1.800 light-years.
More info into the Blog C O M E T O G R A F I A (in Spanish)