Scientists Finally Confirm What's Inside The Moon

Well, the results are in. In the end, the Moon is not composed of green cheese.

A comprehensive analysis has shown that the Moon's interior is actually a solid ball with an iron-like solidity. This, according to academics, will help put to rest a protracted argument regarding whether the Moon's interior is solid or molten and result in a better knowledge of the history of the Moon and, therefore, the Solar System.

Our findings, according to a group led by astronomer Arthur Briaud at the French National Center for Scientific Research in France, "question the evolution of the Moon magnetic field due to its demonstration of the existence of the inner core and support a global mantle overturn scenario that brings significant insights on the timeline of the lunar bombardment in the first billion years of the Solar System."

Seismic data is the most useful tool for probing the internal structure of Solar System objects. Scientists may produce a precise map of the inside of a planet or moon by studying the path taken by quake-generated acoustic waves as they pass through and reflect off the planet or moon's internal material.

The Apollo expedition did record seismic data from the moon, but its resolution is insufficient to assess the status of the inner core. Although there is a fluid outer core, its contents are still up for discussion. With the Apollo data, models with both a solid inner core and a core made completely of fluid do equally well.

Briaud and his colleagues compiled a profile of numerous lunar properties to solve the mystery once and for all by gathering information from space missions and lunar laser range studies. These include its density, the change in its distance from Earth, and the extent of its gravitational interaction with Earth.

They then carried out modeling with several core kinds to see which closely matched the empirical data.

They discovered a number of intriguing things. First of all, active overturn deep inside the lunar mantle is described in the models that most nearly matched what we know about the Moon. Accordingly, the Moon's interior is composed of less dense stuff rising higher and denser material falling toward the center. It has long been suggested that this activity is the cause of the elements found in the Moon's volcanic zones. The team's research adds another piece of evidence to the "for" column.

They also discovered that the lunar core, which has a solid inner core and an outside fluid layer, is strikingly similar to that of the Earth. The inner core's radius is around 258 kilometers (160 miles), whereas the outer core's is approximately 362 kilometers (225 miles). That represents around 15% of the Moon's overall radius.

The study discovered that the inner core has a density of around 7,822 kilograms per cubic meter as well. That comes extremely near to iron's density.

Curiously, a team led by NASA Marshall planetary scientist Renee Weber discovered a similar conclusion in 2011 when studying the lunar core using then-state-of-the-art seismological methods on Apollo data. They discovered proof of a dense inner core with a radius of around 8,000 kilometers and a mass of about 240 kilometers that was solid.

Their findings, according to Briaud and his team, are validation of those earlier discoveries and present a rather compelling argument in favor of an Earth-like lunar core. And this has some fascinating ramifications for the development of the Moon.

We know that the Moon had a strong magnetic field not long after it originated, which started to degrade approximately 3.2 billion years ago. The composition of the lunar core has a significant bearing on how and why the magnetic field vanished since such a magnetic field is produced by motion and convection in the core.

Perhaps we won't have to wait long for seismic confirmation of these results, given that mankind hopes to visit the Moon again in a relatively short period of time.

The research has been published in Nature.