Radiometric dating age of the earth
Scientists have made several attempts to date the planet over the past 400 years.
They've attempted to predict the age based on changing sea levels, the time it took for Earth or the sun to cool to present temperatures, and the salinity of the ocean.
Samples returned from the Apollo and Luna missions revealed ages between 4.4 billion and 4.5 billion years, helping to constrain the age of Earth.
How the moon formed is a matter of debate; while the dominant theory suggests a Mars-size object crashed into Earth and the fragments eventually coalesced into the moon, other theories suggest that the moon formed before Earth. ]In addition to the large bodies of the solar system, scientists have studied smaller rocky visitors that have fallen to Earth. Some are cast off from other planets after violent collisions, while others are leftover chunks from the early solar system that never grew large enough to form a cohesive body.
By examining the existing elements, scientists can calculate the initial quantity of a radioactive element, and thus how long it took for the elements to decay, allowing them to determine the age of the rock.
The oldest of these are between 4.4 billion and 4.5 billion years old.
Samples in Western Australia run 3.4 billion to 3.6 billion years old.
Research groups in Australia found the oldest mineral grains on Earth.
Hematite tubes in volcanic rock in Quebec could have included microbes between 3.77 and 4.29 billion years ago.
Researchers looking at rocks in southwestern Greenland also saw cone-like structures that could have surrounded microbial colonies some 3.7 billion years ago.