The current working theory is our lunar companion formed when an unknown planet smashed into Earth 4.56 billion years ago around the time of the birth of the solar system.
Debris from this collision then combined to form the moon.
But new technology has allowed for much more precise analysis of lunar rocks which has found they are between 4.4 billion and 4.45 billion years old.
Richard Carlson of the Carnegie Institution of Washington, told the LA Times: "Back in the 1970s, you couldn't distinguish between 4.45 and 4.55 billion years.
"Today, we can, and everything we are seeing suggests the 4.4 billion number.
We know the age of the solar system very well - 4.568 billion years, so the Earth may have had two phases of its life - one before the giant impact, and another one greatly modified by the impact."
Carlson theorises that the Earth could have had a "primordial atmosphere" in this earlier stage that could have been blasted off by the impact.
Further evidence of the revised date comes from a number of signs found on Earth of a "major melting event" around 4.45 billion years ago.
The new information has prompted scientists to try to agree once again on a consensus of how it was formed.
A meeting at the Royal Society in London on Monday saw Carlson present his findings.