The discussion centers around the shape of the Oort cloud and why it has not converged to a disk shape, despite the expectation that such a configuration would be more stable. Participants explore various theoretical and observational aspects related to the dynamics of the Oort cloud, including energy loss mechanisms, gravitational interactions, and the nature of collisions among its constituents.
Participants express multiple competing views regarding the dynamics of the Oort cloud and its shape. There is no consensus on the mechanisms preventing the Oort cloud from forming a disk or the implications of its angular momentum.
Limitations include the dependence on assumptions about the nature of collisions, the role of electromagnetic forces, and the observational challenges in determining the properties of distant Oort cloud objects.
Marochnik et al. (1988, Science 242, 547–550) estimated that the angular momentum of the Oort cloud is between 5 × 1052 and 2 × 1053 g cm2 sec-1, two to three orders of magnitude greater than the total angular momentum of the planetary system. However, most of the angular momentum in the present-day Oort cloud is the result of the action of external perturbers over the history of the solar system. In addition, some Oort cloud parameters used by Marochnik et al. tend to be higher than current best estimates. It is shown that the total angular momentum of the current Oort cloud is likely between 6.0 × 1050 and 1.1 × 1051 g cm2 sec-1, and the original angular momentum was likely a factor of 5 less than that.