We've been exploring the Moon since 1969, and despite decades of researching the Earth's only natural satellite, it's clear we still know relatively little about it.
Hovering there in outer space, the Moon is a mystery that's only had 12 people land on it.
Now, new research has given us a closer look at the Moon, and surprise, surprise, it's not made of cheese.
As published on Nautre.com, a team led by astronomer Arthur Briaud has discovered what the Moon is made of, shattering earlier beliefs about the celestial body.
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Instead, the Moon is thought to be a solid ball that has a density similar to iron. Using acoustic waves made by quakes, Briaud and the team are able to analyze its interior materials.
Briaud writes: "Our 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."
Scientists from CNRS, Université Côte d'Azur, the Côte d'Azur Observatory, Sorbonne Université, and the Paris Observatory-PSL delved deeper into the Moon's core, following research from the Apollo 11 mission conducting geological surveys of it.
Several missions used laser ranging to measure the distance between the surface of the Earth and the Moon, working out that the outer core exists over a solid inner.
This inner core is composed of metal and has a density similar to iron, measuring 500 kilometers wide.
This means that this is about 15% of the Moon. Similar to Earth, the mantle has evolved alongside the Moon in a process that’s referred to as lunar mantle overturn.
It explains how iron-rich elements can be found on the surface of the moon, with mantle material carried up as volcanic rock that's left under the lunar crust.
Material that is too dense sinks through the lighter crust material and into the core-mantle.
It's hoped that these findings can help solve the mystery of the moon's magnetic field, which was once 100 times stronger than Earth's but has now almost completely gone.
While we once used to visit the Moon regularly, no one has stepped foot on it in 50 years.
Money and an insecure political climate seem to be the biggest reason we aren't making regular trips to the Moon, but it hasn't stopped us from researching it.
Like we continue to make discoveries here on Earth, the Moon isn't the space enigma it once was.