New research reveals details of the moon’s hidden interior


An illustration of the moon’s interior.

The Moon has a solid iron core just like the Earth. French scientists have analyzed seismic data to find out more about the moon’s interior.


Briefly about “Passive Seismic Experiment”

The first seismograph on the Moon was a passive instrument. The instrument recorded “moonquakes” – it measured how seismic waves moved through the moon, thus providing the first insight into the moon’s interior.

The instrument consisted of four seismometers powered by two solar panels. The four seismometers, one short-period and three long-period, measured moonquakes and meteorite impacts. The seismograph recorded between 100 and 200 impacts during its three-week lifetime.

During Apollo 12, 14, 15 and 16, more advanced seismographs were placed on the Moon and sent data to Earth until 1977.

Fact: Nasa

A drawing of a seismograph.

Of first seismic measurements on the Moon was made on the moon landing in 1969. Buzz Aldrin and Neil Armstrong placed an instrument with four seismometers on the lunar surface that collected data for three weeks.

Since then, several seismic measurements have been made on Earth’s natural satellite. A French research team has used seismic data and precise measurements of the distance between the Earth and the Moon to establish that the Moon has a solid inner core.

In a press release they write that despite the moon’s creation and development still being debated, there is no doubt that, just like the earth, it has a solid inner and a liquid outer core. The results point to a spherical inner core with a diameter of 500 km, roughly 15 percent of the moon’s total size.

Still uncertain what happened to the moon’s magnetic field

The solid inner core appears to consist of a metal with a density similar to that of iron. In addition to giving a figure on the size of the moon’s core, the research also supports a theory that can explain how iron-rich substances ended up on the moon’s surface.

The research, published in Nature, describes how the moon’s mantle has developed over time. The mantle lies between the lunar crust and the outer core. According to the research, iron-rich material may have migrated upwards through the mantle and produced volcanic rock that thus ended up in the lunar crust. Material that rose up, but had a higher density than the mantle, has then sunk down to the boundary between the mantle and the core again.

Another question that scientists are trying to figure out is how it is that the moon’s magnetic field has disappeared. Originally, the moon must have had a magnetic field a hundred times stronger than the Earth’s magnetic field today. The French researchers hope that their study will be able to help find the answer to how and why the field disappeared.

An astronaut on the moon with an instrument.

During the 1969 moon landing, a seismic instrument was placed on the moon.

Source: Ny Teknik – nyheter inom teknik och innovation by

*The article has been translated based on the content of Ny Teknik – nyheter inom teknik och innovation by If there is any problem regarding the content, copyright, please leave a report below the article. We will try to process as quickly as possible to protect the rights of the author. Thank you very much!

*We just want readers to access information more quickly and easily with other multilingual content, instead of information only available in a certain language.

*We always respect the copyright of the content of the author and always include the original link of the source article.If the author disagrees, just leave the report below the article, the article will be edited or deleted at the request of the author. Thanks very much! Best regards!