Artist’s representation of the moon formation event. Copyright: Fahad Sulehria, 2005
The prevailing theory of our moon’s origin is that it was created by a giant impact between a large planet-like object and the proto-Earth. The energy of this impact was sufficiently high that the Moon formed from melted material that was ejected into space. As the Moon cooled, this magma solidified into different mineral components.
Analysis of lunar rock samples thought to have been derived from the original magma has given scientists a new estimate of the Moon’s age.
According to this theory for lunar formation, a rock type called ferroan anorthosite, or FAN, is the oldest of the Moon’s crustal rocks, but scientists have had difficulty dating FAN samples. The research team, led by Lars E. Borg of the Lawrence Livermore National Laboratory, included Carlson of Carnegie’s Department of Terrestrial Magnetism, Boyet -- now at Université Blaise Pascal -- and James N. Connelly of the University of Copenhagen. They used newly refined techniques to determine the age of a sample of FAN from the lunar rock collection at the NASA Johnson Space Center.
The Moon, our nearest celestial neighbor. Image Credit: NASA
This study is the first in which a single sample of FAN yielded consistent ages from multiple isotope dating techniques. This result strongly suggests that these ages pinpoint the time at which the sample crystallized.
“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,” Carlson said.
The Moon is our nearest celestial neighbor and is thought to be linked to the formation and evolution of Earth. Studying our moon can provide clues about how the Earth became habitable for life as we know it. Funding for this work was provided by the Department of Energy, and portions of the work were supported by the NASA Cosmochemistry Program.