Well, the verdict is in. What material is the moon not made of? green cheese at last.
A thorough investigation published in May 2023 revealed that the moon’s inner core is actually a solid ball with a density similar to iron. Researchers hope this will help resolve the long-standing debate about what the moon’s inner heart is. solid or moltenAnd it leads to a more accurate understanding of the history of the Moon and, by extension, the history of the solar system.
“Our results,” wrote a team led by astronomer Arthur Briaud. “The demonstration of the existence of an inner core supports the global mantle overturn scenario, which calls into question the evolution of the lunar magnetic field and provides practical insight into the timeline of lunar bombardment,” the French National Center for Scientific Research said. . “The first billion years of the solar system.”
Investigating the internal composition of solar system objects is best done through seismic data. The way sound waves generated by earthquakes travel through and reflect off material inside a planet or moon can help scientists create detailed maps of the object’s interior.
There is lunar seismic data collected by the Apollo missions, but the resolution is too low to accurately determine the condition of the inner core. We know that there is a fluid outer core.But what it contains is still debatable. The solid inner core and fully fluid core models perform equally well with the Apollo data.
To fully understand this, Briaud and his colleagues collected data from space missions and lunar laser distance measurement An experiment to profile various properties of the moon. These include the degree of deformation due to gravitational interaction with the Earth, changes in distance from the Earth, and density.
Next, modeling was performed with different core types to find the type that best matches the observed data.
They discovered some interesting facts. First, the model that most closely resembles what we know about the Moon depicts active overturning deep within the lunar mantle.
This means that the denser material inside the moon falls toward the center and the less dense material rises upward. This activity has long been proposed as a method of explanation. presence of certain elements In the volcanic regions of the moon. The team’s study adds another point to the “for” tally of evidence.
And they discovered that the moon’s core is very similar to Earth’s. That is, there is an outer fluid layer and a solid inner core. According to their modeling, the outer core has a radius of about 362 km (225 miles) and the inner core has a radius of about 258 km (160 miles). This is about 15% of the total radius of the moon.
The density of the inner core, the research team discovered, is about 7,822 kg per cubic meter. That place is very close. density of iron.
Interestingly, in 2011, a team led by NASA Marshall planetary scientist Renee Weber found similar results using then-state-of-the-art seismology techniques on Apollo data to study the lunar core. they found evidence It consists of a solid inner core with a radius of approximately 240 km and a density of approximately 8,000 kg per cubic meter.
Briaud and his team say their results confirm previous findings and make up a very strong case for an Earth-like lunar core. And this has some interesting implications for the evolution of the Moon.
We know that the Moon had a strong magnetic field not long after it formed, and that it began to decline about 3.2 billion years ago. These magnetic fields are generated by the movement and convection of the core, so what the lunar core is made of has a lot to do with how and why the magnetic fields disappear.
Given humanity’s hopes of returning to the Moon in a relatively short period of time, perhaps we won’t have to wait very long until these discoveries are seismically verified.
This study was published in: nature.
A version of this article was first published in May 2023.
