The Snake Nebula in Ophiuchus
What slithers there? The dark winding lanes visible in part of the constellation Ophiuchus belong to the Snake Nebula. The Snake Nebula is a series of dark absorption clouds made up of Interstellar dust. Interstellar dust grains - composed predominantly of carbon - absorb visible starlight and reradiate much of it in the infrared. This absorption causes stars behind the clouds to be obscured from view, hence the appearance of starless voids on the sky.