Title: Evidence for Missing Matter in the Inner Solar System: Does the Sun have a Dark Disk?

Abstract: The total mass and distribution of dark matter within the Solar system are poorly known, albeit constraints from measurements of planetary orbits exist. We have discovered, however, that different sorts of determinations of the Sun’s gravitational quadrupole moment can combine to yield new and highly sensitive constraints on the mass distribution close to the Sun. These outcomes provide evidence for a non-luminous disk in this region, nominally coplanar with Mercury’s orbit, and we develop how we can use this finding to limit its mass. The mass estimates associated with its known matter components, although uncertain, point to a prominent dark-matter contribution, which merits further investigation. We describe how existing spacecraft studies of the inner solar system support the existence of a circumsolar dust ring, and we note how continuing observational studies of the inner solar system, including the use of space-based quantum technology, can not only help to refine these constraints but also to identify the nature of and the mass of its dark-matter component.