 According to the Lambda Cold-Dark Matter Big Bang Theory, the universe is around 13.8 billion years old. First-generation stars would have contained hydrogen and a little helium and virtually nothing else, because that is all that existed at the time they formed. Very few of these Methuselah first-generation stars are still around. What we see around us today are second-generation stars, including our own Sun. In this segment of the How Old Is It? video book, we'll examine what we know about how old these stars are.