随着越来越多、越远的散射小天体被发现，它们呈现出许多独特的动力学特征，这不但对当前类木行星的演化理论提出了挑战，还预示着太阳系可能存在第9行星，相关研究成为了近几年来国际上新的前沿课题。本项目拟紧密联系这一热点，开展如下研究：(1)详尽分析50AU以外的海王星（高阶）平运动共振的复杂结构，给出散射小天体可能的空间分布；(2)建立第9行星从形成直至演化到当前轨道上的完整模型；(3)第9行星在演化过程中对早期太阳系小天体的轨道激发；(4)第9行星在当前可能的轨道上（数百个天文单位处），对散射小天体空间分布的影响。此外，我们还拟参与对Kuiper带小天体（尤其是散射小天体）的观测。通过本项目的研究，深入了解太阳系边缘的可能结构，寻找第9行星存在的证据，并为揭示整个行星系统的演化历史提供新的线索。

As more and much farther scattered disk objects (SDOs) have been discovered, this population exhibits many peculiar dynamical features, which not only put forward great challenge for the current theory of the evolution of Jovian planets, but also indicate the existence of the distant Planet 9 in the Solar system. The related research has become one of the leading scientific topics in recent years. This project intends to focus on some important questions regarding the Planet 9, including: (1) detailed analyses of the complex structures of the (high-order) Neptune’s mean motion resonances beyond 50AU, and the potential distribution of the SDOs; (2) the complete evolution model of the Planet 9 from the birth region to the final orbit; (3) the excitation of primordial planetesimals during the orbital evolution period of Planet 9 in the early Solar system; (4) the influence of Planet 9 located at the current possible orbit (hundreds of AU) on the distribution of the SDOs. Additional, we would start to join the observation of the Kuiper belt objects, especially for the distant SDOs. Through the execution of this project, we aim to further understand the spatial structure of the edge of the Solar system, seek the evidence for the presence of the Planet 9, and provide new clues for the early evolution history of the entire planet system.