根据行星不稳定性模型，早期的太阳系是一个高度混乱的环境。模拟研究指出，巨行星（木星、土星、天王星和海王星）在形成时距离较近，随后发生了轨道迁移。这一迁移阶段非常不稳定，以至于一到两颗大小与天王星或海王星相似的额外冰巨行星可能已被完全驱逐到星际空间中。最近发表于《Icarus》期刊的一项研究分析了 122 次演化模拟，以调查这些行星扰动如何影响幸存行星的卫星系统，并特别聚焦于天王星。

研究人员发现，在 85% 的模拟情境中，天王星的卫星系统发生了崩溃，卫星仅在极少数情况下得以幸存。在所有卫星幸存的情境中，遗失且被驱逐的行星假设与轨道观测结果极为吻合。该研究指出，天王星的卫星至少经历了两次不稳定状态：第一次是造成天王星自转轴倾斜的巨大撞击，第二次是与被驱逐的巨行星之间的近距离遭遇。这种混乱将卫星系统重塑为目前的配置，表明卫星本身可作为这些遗失世界的重要证据。

具体而言，天王星主要卫星中最小的天卫五（Miranda）展现出极其不寻常的特征，它具有地质活性、冰质比例过高，且外观如同由碎片重建而成。该研究提出，Miranda 是过去行星不稳定性最清晰的物理证据。虽然此模型尚未完全解开遗失行星的谜团，但未来的太空探测任务，例如美国国家航空暨太空总署（NASA）与欧洲太空总署（ESA）预计于 2040 年代联合进行的天王星探测，将可证实 Miranda 是否确实在这段混乱时期后重建，从而有望证实太阳系中遗失行星的存在。

According to planetary-instability models, the early solar system was a highly chaotic environment. Simulations suggest that the giant planets (Jupiter, Saturn, Uranus, and Neptune) formed closer together and subsequently migrated. This migration phase was so unstable that one or two additional ice giants, similar in size to Uranus or Neptune, may have been completely ejected into interstellar space. A recent study published in Icarus analyzed 122 evolution simulations to investigate how these planetary disruptions affected the satellite systems of the surviving planets, focusing particularly on Uranus.

The researchers found that in 85 percent of the simulated scenarios, Uranus's moon system collapsed, and the moons survived in only a small fraction of the cases. In all surviving scenarios, the hypothesis of lost and ejected planets fits the orbital observations exceptionally well. The study suggests that Uranus's moons were destabilized at least twice: first by the giant impact that tilted the planet's axis, and second by close encounters with the ejected giant planets. This chaos reshaped the moon system into its current configuration, indicating that the moons themselves serve as critical evidence of these missing worlds.

Specifically, Miranda, the smallest of Uranus's major moons, displays highly unusual characteristics, being geologically active, disproportionately icy, and appearing as if reconstructed from debris. The study proposes Miranda as the clearest physical evidence of past planetary instability. While this model does not fully resolve the mystery of the missing planets, future space missions, such as the proposed NASA and ESA joint mission to Uranus in the 2040s, could confirm if Miranda was indeed rebuilt after this chaotic era, potentially proving the existence of the solar system's lost planets.