Thanks to meteorites from space, rocks brought back by the Apollo astronauts from the Moon, and sundry other long-distance readings (mostly from satellites) taken of planetary bodies throughout the solar system, scientists have been able to calculate the age of the Earth. They believe the planets, including the Earth, formed between 4.54 to 4.58 billion years ago. In general, most scientists say that the Earth formed somewhere in between-about 4.55 to 4.56 billion years ago.
The reason for the reliance on other space bodies to determine the Earth’s age is simple: The movement of the lithospheric plates around our planet has recycled and destroyed the Earth’s oldest rocks. If there are any primordial rocks left on Earth, they have yet to be discovered. Therefore, scientists must use other means to infer the age of our planet, including the absolute dating of planetary rocks that probably formed at the same time as the Earth.