2025/05/14 by Ryan S. Park, Alexander Berne, A. S. Konopliv +8 · 1 voice
Physics and Astronomy · #Astro and Planetary Science #Planetary Science and Exploration #Space Science and Extraterrestrial Life
paper · pdf · doi:10.1038/s41586-025-08949-5
openalex publication_date 2025/05/14 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/29
Abstract The Moon undergoes periodic tidal forcing due to its eccentric and oblique orbit around the Earth 1 . The response to this tidal interaction drives temporal changes in the lunar gravity field and is sensitive to the satellite’s internal structure 2–4 . We use data from the NASA GRAIL spacecraft 5–9 to recover the time-varying lunar gravity field, including a degree-3 gravitational tidal Love number, k 3 . Here, we report our estimated value of k 3 = 0.0163 ± 0.0007, which is about 72% higher than that expected for a spherically symmetric moon 10 . Such a large k 3 can be explained if the elastic shear modulus of the mantle varies by about 2–3% between the nearside and farside 4 , providing an observational demonstration of lateral heterogeneities in the deep lunar interior. This asymmetric structure suggests preservation of a predominantly thermal anomaly of roughly 100–200 K in the nearside mantle that formed surface mare regions 3–4 billion years ago 11 and could influence the spatial distribution of deep moonquakes 12 .