Scientists believe the Earth is approximately 4.54 billion years old. This age is determined through various methods, primarily radiometric dating.
Radiometric Dating: A Key Tool
Radiometric dating relies on the decay of radioactive isotopes within rocks. These isotopes decay at a predictable rate, known as their half-life. By measuring the ratio of parent isotopes to their decay products, scientists can calculate the age of the rock.
Evidence from Different Sources
Evidence supporting this age comes from multiple sources:
- Meteorites: Many meteorites, remnants from the early solar system, have been dated to around 4.56 billion years old.
- Lunar Samples: Rocks brought back from the Moon by Apollo missions have also been dated to approximately 4.5 billion years old.
- Earth's Oldest Rocks: The oldest known rocks on Earth, found in the Canadian Shield, are about 4 billion years old.
Understanding the Earth's Formation
These findings indicate that the Earth formed shortly after the solar system itself, around 4.6 billion years ago. The early Earth was a very different place, with a molten surface and a constant bombardment of asteroids and comets. Over time, the Earth cooled and differentiated, eventually forming the continents and oceans we know today.
