柯伊伯带是一个距离太阳约 30 到 50 AU 的冰冻碎屑区域，于 1990s 首次被确认，并保存了太阳系约 4.6 billion years ago 形成时的物质。过去 30 years，天文学家已编目约 4,000 个 Kuiper Belt objects，但随著新巡天资料到来，预期数量将约增加 10x，尤其是 2025 开始运作、并有 JWST 支援的 Vera C. Rubin Observatory 的 LSST。这次扩大的普查锁定几个主要未知：是否存在隐藏行星、该带在 50 AU 之外延伸多远，以及轨道结构揭示了哪些早期行星迁移资讯。

一个关键的动力学特征是已知位于 44 AU 附近的 kernel，与 cold classical objects 有关，并可能与海王星迁移及 4 billion years ago 之后的一次轨道「jump」相关。2025 的 Princeton 分析使用了 1,650 个 KBOs，约为 2011 年 kernel 研究样本量的 10x，并确认了 44 AU 的群聚，同时发现了可能位于 43 AU 附近的内部 kernel 证据。在行星搜寻方面，Planet Nine 仍是位于数百 AU 的假设天体，而提出的较小 Planet Y 被建模在约 80 到 200 AU；Rubin 可能侦测到此类天体，但在 200 到 400 AU 的预期亮度、反照率与大气性质仍高度不确定。

该带外部结构也是另一个统计异常：观测到的族群在 Kuiper cliff 附近的 50 AU 急遽下降，而许多系外碎屑盘明显更大。2024 的一项研究回报了位于 100 AU 附近天体的候选迹象，若获确认，可能使太阳系从看似离群值转向更接近平均的盘尺度；若未获确认，这种尖锐截断仍是强限制。无论哪种结果都具资讯价值：若侦测到大型远距天体，将扩充行星清单；若在已定义距离上限内未侦测到，则会收紧对行星形成效率的估计并降低模型不确定性。

The Kuiper Belt is a frozen debris region roughly 30 to 50 AU from the Sun, first recognized in the 1990s, and it preserves material from the solar system’s formation about 4.6 billion years ago. Astronomers have cataloged about 4,000 Kuiper Belt objects over the last 30 years, but expect roughly a 10x increase as new surveys arrive, especially from the Vera C. Rubin Observatory’s LSST, which began operations in 2025, with support from JWST. This expanded census targets major unknowns: whether hidden planets exist, how far the belt extends beyond 50 AU, and what orbital structures reveal about early planetary migration.

A key dynamical feature is the known kernel near 44 AU, tied to cold classical objects and potentially to Neptune’s migration and a later orbital “jump” more than 4 billion years ago. A 2025 Princeton analysis used 1,650 KBOs, about 10x the sample size of a 2011 kernel study, and confirmed the 44 AU cluster while finding evidence for a possible inner kernel near 43 AU. On the planet-search side, Planet Nine remains hypothetical at several hundred AU, while a proposed smaller Planet Y is modeled at about 80 to 200 AU; Rubin may detect such objects, but expected brightness, albedo, and atmospheric properties at 200 to 400 AU remain highly uncertain.

The belt’s outer structure is another statistical anomaly: observed populations drop sharply near 50 AU at the Kuiper cliff, whereas many extrasolar debris disks are significantly larger. A 2024 study reported candidate signs of objects near 100 AU, which, if confirmed, could shift the solar system from an apparent outlier toward a more average disk scale; if not confirmed, the sharp cutoff remains a strong constraint. Either outcome is informative: detections of large distant bodies would expand planetary inventories, while non-detections up to defined distance limits would tighten estimates of planet-formation efficiency and reduce model uncertainty.