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After the Big Bang, the universe expanded and cooled sufficiently for hydrogen atoms to form. In the absence of light from the first stars and galaxies, the universe entered a period known as the cosmic dark ages. The first stars and galaxies appeared several hundred million years later and began burning away the hydrogen fog left over from the Big Bang, rendering the universe transparent, like it is today. Researchers have now confirmed the existence of a distant, faint galaxy typical of those whose light burned through the hydrogen atoms; the finding should help them understand how the cosmic dark ages ended.