Stellar occultations provide a powerful tool to explore objects of the outer solar system. The Gaia mission now provides milli-arcsec accuracy on the predictions of these events and makes possible observations that were previously unthinkable. Occultations return kilometric accuracies on the three-dimensional shape of bodies irrespective of their geocentric distances, with the potential of detecting topographic features along the limb. From the shape, accurate values of albedo can be derived, and if the mass is known, the bulk density is pinned down, thus constraining the internal structure and equilibrium state of the object. Occultations are also extremely sensitive to tenuous atmospheres, down to the nanobar level. They allowed the monitoring of Pluto’s and Triton’s atmospheres in the last three decades, constraining their seasonal evolution. They may unveil in the near future atmospheres around other remote bodies of the solar system. Since 2013, occultations have led to the surprising discovery of ring systems around the Centaur object Chariklo, the dwarf planet Haumea and the large trans-Neptunian object Quaoar, while revealing dense material around the Centaur Chiron. This suggests that rings are probably much more common features than previously thought. Meanwhile, they have raised new dynamical questions concerning the confining effect of resonances forced by irregular objects on ring particles. Serendipitous occultations by km-sized trans-Neptunian or Oort objects have the potential to provide the size distribution of a population that suffered few collisions until now, thus constraining the history of primordial planetesimals in the 1–100 km range.

恒星掩星为探索外太阳系的天体提供了强大的工具。Gaia 任务现在为这些事件的预测提供了毫秒角秒的精度，并使以前无法想象的观测成为可能。掩星返回物体三维形状的千米精度，而不管它们的地心距离如何，都有可能检测沿肢体的地形特征。从形状中可以得出反照率的准确值，如果质量已知，则确定堆积密度，从而约束物体的内部结构和平衡状态。掩星对薄弱的气氛也非常敏感，低至纳棒水平。他们允许在过去三十年中监测冥王星和海卫一的大气层，限制了它们的季节性演变。它们可能会在不久的将来揭开太阳系其他遥远天体周围的大气层的面纱。自 2013 年以来，掩星导致在半人马天体 Chariklo、矮行星 Haumea 和大型跨海王星天体 Quaoar 周围惊人地发现了环系统，同时揭示了半人马凯龙周围的致密物质。这表明年轮可能比以前认为的要常见得多。同时，他们提出了关于不规则物体对环粒子施加的共振限制效应的新动力学问题。公里大小的跨海王星天体或 Oort 天体的偶然掩星有可能提供迄今为止很少遭受碰撞的种群的大小分布，从而将原始小行星的历史限制在 1-100 公里范围内。