'Hidden Depths': NASA's new evidence suggests our Moon has a secret layer of molten rock

Recent research indicates that the moon may possess a molten layer of rock situated between its core and solid exterior, a hypothesis that has intrigued scientists for years. This conclusion is based on new evidence regarding the moon's response to the gravitational forces exerted by Earth and the sun.

Similar to Earth, which experiences tidal effects caused by the gravitational pull of the moon and sun, the moon also undergoes subtle changes in its shape and gravitational field due to these tidal forces. While Earth's oceans visibly rise and fall, the moon lacks such bodies of water, making its tidal responses more subtle. However, these responses provide critical insights into the moon's internal structure.

The research builds upon previous studies that measured the moon's tidal changes over a month. In contrast, the current study utilized data collected over a year by NASA's Gravity Recovery and Interior Laboratory (GRAIL) mission and the Lunar Reconnaissance Orbiter. This comprehensive data set allowed scientists to examine the monthly and yearly distortions in the moon's shape and gravitational field, which were then combined with existing lunar information, including the moon's average density.

The findings revealed that incorporating a softer layer at the base of the moon's mantle more accurately reproduced the observed gravitational measurements. This suggests the presence of a viscous layer deep within the moon, enhancing the argument for a molten layer beneath its surface.

The study also speculates that if such a molten layer exists, it could be composed of ilmenite, a titanium-rich material. However, researchers still face questions regarding the source of heat that would maintain the molten state of this layer. Further investigation is necessary to ascertain the composition of the layer and the mechanisms responsible for its warmth.

As the quest to understand the moon’s internal structure continues, these gravity measurements offer promising clues that could reshape our understanding of our celestial neighbour.