Astronomers think that the Earth likely formed at the same time as all of 1 the other rocky materials in our solar system, including the oldest meteorites. The oldest meteorites ever found on Earth contain nearly equal amounts of both Uranium-238 (U-238) and Lead-206 (Pb-206). The half-life of the U-238/Pb-206 decay pair is 4.5 billion years. According to this absolute age-dating method, what is Earth's age? (Don't forget units!)