Distance Between the Earth and Moon

Surprise! The Earth And Moon May Be 60 Million Years Older Than We Thought

10 Jun , 2014 by

Wondering why a new research team says the Earth and the Moon is 60 million years older than previously believed? Well, it’s a gas. It has to do with the proportion of different gas types that have stuck around since the Earth was formed about 4.5 billion years ago.

Since Earth had no solid surface at the time, traditional geology doesn’t really work — there’s no rock layers to examine, for example. So while the geologists caution we’ll likely never know for sure when the Earth came together, a new dating method for the gases show it was earlier than believed, they said.

To back up a step, the leading theory for how the Moon formed is that a Mars-sized object smashed into our planet, created a chain of debris, and over a long time gradually came together and formed the Moon. There’s been a flurry of news on this event in recent days. Different science groups have found evidence of the crash in Earth and Moon materials, and said it could explain why the Moon’s far side is so rugged compared to the near side.

For this study, Guillaume Avice and Bernard Marty (who are both geochemists from the University of Lorraine in Nancy, France) examined xenon gas in quartz found in Australia (previously believed to be 2.7 billion years old) and South Africa (3.4 billion years old).

64% illuminated waning gibbous Moon on August 26, 2013. Credit and copyright: Themagster3 on Flickr.

64% illuminated waning gibbous Moon on August 26, 2013. Credit and copyright: Themagster3 on Flickr.

“Recalibrating dating techniques using the ancient gas allowed them to refine the estimate of when the Earth began to form,” stated the Goldschmidt Geochemistry Conference in Sacramento, California, where this was presented today (June 10). “This allows them to calculate that the Moon-forming impact is around 60 million years (+/- 20 m. y.) older than had been thought.”

This also affects calculations concerning when the Earth’s atmosphere formed. Since the atmosphere could not have stuck around after the big crash, this means that the previous estimate of 100 million years after the solar system’s formation wouldn’t work. So if the Earth and the Moon are 60 million years older, the Earth’s atmosphere formed about 40 million years after the solar system’s formation.

It’ll be interesting to see if other scientists agree with the analysis.

Source: Goldschmidt Geochemistry Conference

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Torbjorn Larsson OM
Torbjorn Larsson OM
June 10, 2014 4:00 PM
The first robust dating I heard of for the Tellus-Theia collision making Earth-Moon was using highly siderophile elements (HSEs) to constrain the evolution of the late accretion. [“Highly siderophile elements in Earth’s mantle as a clock for the Moon-forming impact”, Jacobson et al, Nature 2014] That indeed puts the impact at 95 +/- 32 million years after condensation of the systems’ first solids. That method stresses these, presumably less precise, isotope dating methods a lot. They exclude the 40 million base date at 97.5 % and the 60 million year 1 sigma limit at 1 sigma. If the used dating is Xe-I [ http://en.wikipedia.org/wiki/Iodine-129 ; used for meteorite age dating], it is a radiometric clock. The paper says… Read more »