The Moon\u2019s interior<\/p>\n Because we know the gravitational pull of the moon, and we also know its volume, we can calculate its average density. But that doesn\u2019t really tell the whole story about what the moon is made from, only the average value. We also sent landers to the moon and took photos of the lunar surface, piecing together what the crust is made of.<\/p>\n But that still doesn\u2019t tell the whole story.<\/p>\n Since the 1960s, several missions have been sent to the Moon, including the famous Apollo missions. In addition to exploring the surface, Apollo astronauts also set up scientific experiments and brought back lunar rocks for analysis. These missions provided direct observations and samples that have been crucial in understanding the Moon\u2019s composition. Decades later, in 2024, the Chang\u2019e mission would bring the first samples from the far side of the moon<\/a>.<\/p>\n The Apollo astronauts did something else: they left seismomenters on the moon. These seismometers offered the first serious clues regarding the interior of the moon and what the moon is made of. That approach is also how researchers know what\u2019s inside of our own planet (with the key difference that we have way, way more seismometers on Earth).<\/p>\n Now, a new seismometer on the moon has brought<\/a> the final piece of the puzzle.<\/p>\n \u201cOur results question the evolution of the Moon magnetic field thanks to its demonstration of the existence of the inner core and support a global mantle overturn scenario that brings substantial insights on the timeline of the lunar bombardment in the first billion years of the Solar System,\u201d the researchers wrote in their paper.<\/p>\n Seismics shows what\u2019s inside the moon<\/p>\n Studying the inner composition of objects in the Solar System<\/a> is best done through seismic data<\/a>. Seismic waves (which are essentially acoustic waves) propagate differently through different materials. So these waves generated by moonquakes can reveal the inner structure of the moon, depending on what they\u2019re passing through. The end result is a sort of geological X-ray. <\/p>\n India\u2019s Chandrayaan-3, which touched down on the moon in August 2023, has detected the first lunar quake in over 50 years. However, the researchers at C\u00f4te d\u2019Azur University in France didn\u2019t have access to this data when they first embarked on this study, so they had to rely on old Apollo-era data. The challenge is that ancient data is low-resolution by today\u2019s standard \u2014 too poor to determine the lunar core\u2019s state. <\/p>\n Seeking a way forward, the researchers gathered additional data from space missions and lunar laser ranging experiments and created a profile of the moon\u2019s features. This includes its density and variation in its distance from Earth, among other things. They then did modeling with different core types to find which matched best the observational data.<\/p>\n The researchers made several important findings. First, they found that denser material inside the moon falls towards the center, and less dense material rises upwards. This has been previously suggested by researchers as a way of explaining the presence of certain elements in volcanic regions of the moon. But that\u2019s only one part of the picture.<\/p>\n The researchers also found that the lunar core is very similar to that of the Earth, with an outer fluid layer<\/a> and a solid inner core. The core <\/a>is about 500 kilometers in diameter, or 15% of the Moon\u2019s width. Curiously, back in 2011,<\/a> a team led by NASA scientists found a similar result using seismological techniques on Apollo data to study the lunar core. The fact that the two studies line up using two different techniques lends more credibility to this conclusion. <\/p>\n The moon\u2019s interior still has some mysteries<\/p>\n While the finding sheds some light on the moon\u2019s structure, there are still many more mysteries that remain unsolved, such as what happened to its magnetic field.<\/p>\n Unlike Earth, the Moon doesn\u2019t have active plate tectonics. This means its surface doesn\u2019t get recycled through the kind of geological processes seen on Earth. But the moon did experience some changes.<\/p>\n Not long after it formed, the moon<\/a> had a powerful magnetic field, which then began to decline about 3.2 billion years ago. The field was generated by motion and convection in the core.<\/p>\n It gets even more interesting. Remember the gravity data we were mentioning? A 2025 study<\/a> using that very data found that the moon\u2019s deep interior is probably asymmetrical. This asymmetry was apparently caused by intense volcanism on its nearside billions of years ago that helped shape its surface features.<\/p>\n![\"The](\"https:\/\/www.newsbeep.com\/il\/wp-content\/uploads\/2025\/11\/1024px-The_Moon_August_11_2019.jpg\")
<\/a>Image credits: Wikipedia Commons.<\/p>\n![\"\"](\"https:\/\/www.newsbeep.com\/il\/wp-content\/uploads\/2025\/11\/subsurface-teren.jpg\")
<\/a>AI-generated illustration<\/p>\n