The moon is 4.36 billion years old, up to 200 million years younger than thought, according to analysis of lunar rocks reported in the latest issue of Nature.
The estimate comes from a new dating of isotopes of lead and neodymium found in samples of ferroan anorthosite, a crustal rock that derives from magma.
A common theory for the origin of the moon is that it was created by an impact between a large planet-sized object and the nascent earth. The molten material, or magma, that was ejected from this giant collision progressively cooled, hardening into earth’s rocky, barren and airless satellite.
“The extraordinarily young age of this lunar sample either means that the moon solidified significantly later than previous estimates, or that we need to change our entire understanding of the moon’s geochemical history,” said Richard Carlson of the Carnegie Institution for Science in Washington.