For long, there has been curiosity about what Earth’s nearest neighbour is made of and debates about whether the Moon’s inner core is solid or liquid have spurred on.
According to new research, based on an extensive investigation, the inner core of the Moon is a solid ball with a density similar to that of iron. This opens the door to a more accurate understanding of the Moon and our solar system.
Seismic data effectively examine the inner composition of the objects in the solar system. Scientists investigate how the acoustic waves generated by quakes move through and reflect from the material inside a planet or moon to create a detailed map of the interior, according to a Science Alert report. While it’s known that the Moon’s outer core is fluid, the composition of the inner core has been under debate for a while.
Seismological data collected by the Apollo mission provided the first records of the Moon’s inner structure, but its resolution was too low to accurately determine the state, according to the a research paper published in the journal Nature.
Hence, scientists collected data from space missions and lunar laser ranging experiments to compile a profile of lunar characteristics such as the degree of its deformation by gravitational interaction with Earth, the variation in its distance from Earth, and its density, the Science Alert report further explains. This was followed by conducting modelling with various core types to figure out which matched most closely with the observational data. The research team for this study was led by astronomer Arthur Briaud of the French National Centre for Scientific Research in France.
The findings showed that the lunar core has an outer fluid layer and a solid inner core, similar to Earth. According to the scientists’ modelling, the outer core has a radius of about 362 kilometres (225 miles), and the inner core has a radius of about 258 kilometres (160 miles). That's about 15 per cent of the entire radius of the Moon, according to the Science Alert report. Furthermore, the density of the inner core was found to be about 7,822 kilograms per cubic meter which is very close to that of iron.
The findings question the evolution of the Moon’s magnetic field because it demonstrates the inner core. They also “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," Briaud explains in the Science Alert report.
Similar results were found in 2011 by a team led by Nasa Marshall planetary scientist Renee Weber. The team used seismological techniques on Apollo data to examine the lunar core and found evidence of a solid inner core with a radius of about 240 kilometres and a density of about 8,000 kilograms per cubic meter, the Science Alert report adds. The current findings confirm previous results and present a strong case for a solid inner core.