scattereddisk

Scattereddisk, also called the scattered disc, refers to a distant population of icy minor planets in the outer solar system. These objects occupy distant, highly eccentric and moderately inclined orbits, typically with perihelia near Neptune’s orbit and semimajor axes that span from tens to thousands of astronomical units. Scattered-disc objects often have eccentricities between 0.2 and 0.8 and inclinations that can exceed 40 degrees, placing them outside the main Kuiper belt and outside many long-term resonant groups.

Origin and dynamics are linked to Neptune’s early migration. As the giant planet moved outward, gravitational encounters scattered a large number of planetesimals into elongated, off-plane orbits. Ongoing perturbations by Neptune can further modify these trajectories, occasionally sending objects inward toward the inner solar system or outward toward interstellar space. Because of their unstable and energetically excited orbits, scattered-disc objects are less dynamically protected than classical Kuiper belt objects and can be perturbed into various fates over astronomical timescales.

Relationship to other populations is important for classification. The scattered disc forms part of the broader family of trans-Neptunian objects (TNOs) and is distinguished from hot and cold classical Kuiper belt objects, resonant bodies, and detached objects by its path-crossing interactions with Neptune. Observationally, biases in detection make precise population estimates difficult, but the scattered disc is widely regarded as substantial, with hundreds of known members and many more likely undiscovered.