Order the following events to describe the process of how comets from the Oort Cloud are formed and interact with the solar system: A) Gravitational disturbances from nearby stars influence Oort Cloud objects, B) Icy bodies in the Oort Cloud are perturbed into the inner solar system, C) These bodies exhibit long orbital periods as they approach the sun, D) The objects coalesce to form larger bodies in the outer solar system.

The icy bodies that form the Oort Cloud first coalesce into larger objects in the outer solar system (D). Once the Oort Cloud is established, gravitational disturbances from nearby stars or passing clouds (A) can alter the orbits of these bodies. These disturbed objects are then nudged into trajectories that bring them into the inner solar system (B). As they approach the sun, they display very long orbital periods before returning to the distant Oort Cloud again (C). For example, a comet that once orbited the Sun every few thousand years can be knocked into a 10,000‑year orbit after a stellar encounter, then travel inward and become visible.