Barnard 72 in Ophiuchus.
Also dark nebulae Barnard 68, 69, 70, and part of 74 from right to left.

The very dense molecular cloud Barnard 68 lets no visible starlight through, obscuring the light of 1000 stars. It is 1/2 of a light year accross and is 500 light years away. The cloud's mass is about twice that of the Sun, and it measures about half a light-year across. Barnard 68's well-defined edges and other features show that it is on the verge of gravitational collapse within the next 100,000 years or so, and is on its way to becoming a star.

For a wide view that shows where the Snake Nebula is, see the Pipe Nebula image:
http://www.pbase.com/image/151746407