The Comet Reservoir Nobody Has Ever Seen
From Unknown Universe · 11:20
Show by Reyna Rogers
A trillion icy worlds surround the Sun in a shell a light-year across, holding the most pristine material in the solar system, and no telescope has ever seen a single piece of it. Reyna follows Jan Oort's 1950 inference from long-period comet orbits, the scattering story, the mass problem, and the search for a direct detection. What was observed? Long-period comets arriving from every direction on highly elongated orbits, with aphelia clustered at tens of thousands of astronomical units. How was it measured? Comet orbit reconstruction, plus the dynamics of passing stars and the galactic tide; no Oort cloud object has ever been imaged. Why is it important? The cloud would be the largest structure in the solar system and the source of all long-period comets, preserving material unchanged since the planets formed. What explanations are supported? Planetesimals scattered outward by the giant planets and circularised by stars and the galactic tide; a captured interstellar contribution remains possible. What remains unknown? The cloud's true mass and structure, whether the Hills cloud holds most of it, and whether Sedna belongs to it. Sources: Oort 1950; Dones et al. 2015; Brasser and Morbidelli 2013; Fouchard et al.; NASA Oort cloud overview 2025.
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