A massive vacuum in the universe London - Arabstoday In a sky filled with bright stars, this image appears to show a massive black hole in its centre. But, rather than being a genuine black hle, the eerily dark \'hole\' in this photograph is a cloud of matter -  known to astronomers as a dark molecular cloud - which blocks all light from passing through it. The interiors of molecular clouds are some of the coldest and most isolated places in the universe. The bizarre sight is formed due to a high concentration of dust and molecular gas absorbing practically all the visible light emitted from background stars. Pictured is Barnard 68, which is one of the most notable molecular clouds and is towards the constellation Ophiuchus. Astronomers say because no stars are visible, this indicates that Barnard 68 is relatively nearby. But this is still about 500 light-years away and half a light-year across. It is not known exactly how molecular clouds like Barnard 68 form. But scientists do know 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. In infrared light, it is also possible to look right through the cloud.