The existence of pristine gas that formed minutes after the Big Bang explosion some 13.7 billion years ago, had been predicted, but never before observed.

The clouds, which are located about 12 billion light-years from Earth within the constellations Ursa Major and Leo, were found serendipitously during an ongoing study to characterise gas in distant galaxies.

In analysing the light coming from quasars (active nuclei of distant galaxies), astronomers realised the rays had passed through gas that contained only hydrogen and deuterium, elements that formed minutes after the Big Bang.

via ABC Science