The last giant impact on Earth is thought to have formed the Moon¹. The timing of this event can be determined by dating the different rocks assumed to have crystallized from the lunar magma ocean (LMO). This has led to a wide range of estimates for the age of the Moon between 4.35 and 4.51 billion years ago (Ga), depending on whether ages for lunar whole-rock samples^2,3,4 or individual zircon grains^5,6,7 are used. Here we argue that the frequent occurrence of approximately 4.35-Ga ages among lunar rocks and a spike in zircon ages at about the same time⁸ is indicative of a remelting event driven by the Moon’s orbital evolution rather than the original crystallization of the LMO. We show that during passage through the Laplace plane transition⁹, the Moon experienced sufficient tidal heating and melting to reset the formation ages of most lunar samples, while retaining an earlier frozen-in shape¹⁰ and rare, earlier-formed zircons. This paradigm reconciles existing discrepancies in estimates for the crystallization time of the LMO, and permits formation of the Moon within a few tens of million years of Solar System formation, consistent with dynamical models of terrestrial planet formation¹¹. Remelting of the Moon also explains the lower number of lunar impact basins than expected^12,13, and allows metal from planetesimals accreted to the Moon after its formation to be removed to the lunar core, explaining the apparent deficit of such materials in the Moon compared with Earth¹⁴.

对地球的最后一次巨大撞击被认为形成了月球¹ 号。这一事件的时间可以通过对假设是从月球岩浆海洋 （LMO） 结晶的不同岩石进行测年来确定的。这导致对 4.35 至 45.1 亿年前 （Ga） 之间的月球年龄的估计范围很广，具体取决于月球全岩样本的年龄^2,3,4 还是单个锆石颗粒^5,6,7。在这里，我们认为，月球岩石中频繁出现大约 4.35 Ga 的年龄，而锆石年龄大约在同一时间出现峰值⁸，这表明月球的轨道演化驱动了再熔化事件，而不是 LMO 的原始结晶。我们表明，在穿过拉普拉斯平面过渡⁹ 期间，月球经历了足够的潮汐加热和熔化，以重置大多数月球样本的形成年龄，同时保留了早期的冻结形状¹⁰ 和罕见的、早期形成的锆石。这种范式调和了对改性活生物体结晶时间估计的现有差异，并允许在太阳系形成后的几千万年内形成月球，这与类地行星形成的动力学模型一致¹¹。月球的重熔还解释了月球撞击盆的数量少于预期的^12,13，并允许在月球形成后吸积到月球上的行星的金属被转移到月球核心，解释了与地球相比，月球中此类物质的明显不足¹⁴。