It was during the Dark Ages that the universe cooled enough to allow molecular hydrogen to form, filling the cosmos with a diffuse cloud of electrically-neutral gas.
早期期间宇宙冷却到足以使一种弥漫的电中性气体云充满了宇宙的分子氢形成。
2
Orion Nebula Area by Fabian Neyer. A deep image of part of the constellation of Orion showing swirling pink clouds of hydrogen and dark clumps of interstellar dust.
猎户座大星云区这是猎户星座的部分近照，图中粉红色旋转着氢气云团，暗色的是星际尘埃团。
3
Because hydrogen atoms trap light, the young universe entered its "dark ages."