What is the core made of

Moonquakes over 30 years ago reveal the inner structure of the earth's satellite

The moon

Tempe (USA) - The moon is anything but a rigid block of rock. Similar to the earth, there is a hard core inside, which is surrounded by liquid melt. American scientists who had evaluated seismic data from the 1970s with new methods have now gained a more detailed insight into the inner structure of the moon. They published their results, which help improve the geological picture of the moon, in the journal "Science".

During the moon landings between 1969 and 1972, the astronauts placed four sensitive seismometers on the dusty surface in order to be able to record the vibrations after moonquakes. Up until 1977, this enabled data to be obtained that enabled an insight into the interior of the satellite. "Now we have analyzed the seismograms from the Apollo mission again," report Renee C. Weber from the Nasa Marshall Space Flight Center and his colleagues from Arizona State University in Tempe. The researchers used modern computer programs such as those currently used to analyze earthquakes.

The registered seismic waves of the quakes penetrated far into the interior of the moon and were scattered and reflected by the different layers. The researchers were able to determine the solid lunar core, which has a high proportion of iron, to a diameter of 480 kilometers. A liquid layer about 90 kilometers thick circulates around it. The transition to the mantle is dominated by a partially melted layer 150 kilometers thick.

This study proves that geologically, the moon is not dead, as researchers had long believed. This assumption is also supported by gas eruptions that could have shaken the earth's satellite about a million years ago. The cause is considered to be the outgassing of magma residues in the interior of the moon.