Gas Clouds

Gas Clouds are one of the three major structures of the Universe.  They permeate the Galaxies and the Galaxy Clusters.  These are essentially hydrogen gas clouds (90%) and they are massive.  Remember, immediately after the Big Bang approximately ¼ of the matter in the universe was converted to Helium nuclei since it was too hot for electrons to stick to the nucleus.  But as the universe cooled these nuclei found it to more stable to join with an electron and form the hydrogen atom.  Most of the universe at this early point consisted of hydrogen and, in fact, the Gas clouds observed today within and around galaxies consist of this hydrogen.  So it is not surprising in retrospect that there are huge gas clouds in the universe.  All of these are likely to form stars.

Largely misunderstood until NASA put the Chandra X-ray telescope into earth orbit, the gas clouds have reveled themselves easily to x-ray investigation.