This eerie patch of blackness in the middle of a busy star cluster may look like a rather misshapen black hole, but it's actually something even stranger. It's also quite possibly the loneliest, darkest, coldest place in the entire cosmos.
This is Barnard 68, and it's what's known as a dark molecular cloud. Basically, the dust and gas that makes up Barnard 68 is so tightly packed together that it blocks out all the light behind it. The result might look like some alien civilization tore apart the fabric of the universe and opening up a gateway to the howling void, but thankfully - or unfortunately, I guess, depending on how you feel about the howling void - it's just gas. Make that a lot of gas.
Here's some additional info on this particular patch of darkness:
The eerily dark surroundings help make the interiors of molecular clouds some of the coldest and most isolated places in the universe. One of the most notable of these dark absorption nebulae is a cloud toward the constellation Ophiuchus known as Barnard 68, pictured above. That no stars are visible in the center indicates that Barnard 68 is relatively nearby, with measurements placing it about 500 light-years away and half a light-year across. It is not known exactly how molecular clouds like Barnard 68 form, but it is known that these clouds are themselves likely places for new stars to form. In fact, Barnard 68 itself has been found likely to collapse and form a new star system.
It should be pointed out that this molecular cloud only looks pitch black in the optical wavelengths that are familiar to us. Venture into different wavelengths, such as infrared, and you can see the stars behind Barnard 68 just fine, as you can see here.