How old is the Earth?

Scientists estimate that Earth formed about 4.54 billion years ago, give or take around 50 million years, from dust and rock circling the young Sun. Because plate tectonics and erosion have recycled the oldest crust, the age comes mainly from radiometric dating of meteorites, which formed at the same time as the planets. In 1956 geochemist Clair Patterson used lead isotopes in meteorites to calculate an age of about 4.55 billion years, a figure that still stands. The oldest known Earth minerals are zircon crystals from the Jack Hills in Western Australia, about 4.4 billion years old. The Moon formed shortly after Earth, probably from a giant collision.