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The Lunar Core

1/07/2011 11:42:00 PM

As the self-professed "Astronaut Seismologist," I am very excited by yesterday's NASA announcement confirming that the Moon does indeed have a core.  The news accompanies a report published in the journal Science by Weber et al.  Having just read the paper and its extensive supplemental material, I will devote this post to conveying my initial impressions of the research.  SPACE.com, Science Daily, Science, Discovery News, and Daily Mail had very public-friendly writeups on this story that are worth a look too.  If you prefer to listen, check out this NPR Science Friday interview with Renee Weber:

The gist of the paper is that the moon has a solid inner core, a liquid outer core, and a mushy partially molten region above the outer core.  The Earth has all of these same features in its deep interior too.  Scientists have long suspected the Moon to have a core due to indirect evidence such as the composition of lunar rock samples or the lunar Love numbers.  The Weber et al. paper provides the first direct evidence of seismic wave reflections off the lunar core.

This finding is a big deal because by knowing the structure of the lunar core, we can understand the moon's present and past thermal state, the history of the lunar dynamo, and the origin and evolution of the Moon.  After all, the prevailing theory is that the Moon formed from a giant impact into the Earth, so its history tells us a great deal about our own planet too.