Cosmic voids are vast empty spaces between galaxy filaments (galaxy filaments are the largest known structures in the universe) which contain few or no galaxies. The recent study in “Evidence for Large-scale Fluctuations in the Metagalactic Ionizing Background Near Redshift Six” revealed that the intergalactic space was loaded up with gas that was much less transparent than it presently is, with variations from place to place, about 12 billion years prior.
On a starry night directing your telescope towards the south of Orion belt, will reveal a cloudy object which is nothing but a nebula. Probably from its appearance only, nebula got its name as, ‘Nebula’ is Latin for word cloud or mist. It will not be an exaggeration if we call it one of the spectacular objects holding many secrets of the universe.