From Wikipedia

Earth Story
Episode One

The Time Travellers

The age of the Earth has been determined to be 4.54 billion years (4.54 × 10⁹ years ± 1%). This age is based on evidence from radiometric age dating of meteorite material and is consistent with the ages of the oldest-known terrestrial and lunar samples.

Following the scientific revolution and the development of radiometric age dating, measurements of lead in uranium-rich minerals showed that some were in excess of a billion years old. The oldest such minerals analyzed to date – small crystals of zircon from the Jack Hills of Western Australia – are at least 4.404 billion years old. Comparing the mass and luminosity of the Sun to the multitudes of other stars, it appears that the solar system cannot be much older than those rocks. Ca-Al-rich inclusions (inclusions rich in calcium and aluminium) – the oldest known solid constituents within meteorites that are formed within the solar system – are 4.567 billion years old, giving an age for the solar system and an upper limit for the age of Earth.