Surface brightness photometry of the night sky with experiments aboard several rockets and spacecraft indicates a significant enhancement of the brightness of the zodiacal light relative to the sun in the 1700 to 3000 A spectral region. This enhancement is most likely due to Mie scattering by non-absorbing (dielectric) particles with a mean radius of ~0.05µ and a real index of refraction which increases rapidly from ~1.4 to ~2.0 at ~2000 A, where most optical materials have an absorption edge (and exhibit a similar phenomenon). Assuming the visible zodiacal light is produced by 10 to 30µ particles, the number density of 0.5µ particles must be ~3 × 105 times greater, in good agreement with size distributions from crater counts and space probe particle detectors. Ultraviolet observations of comets indicate the enhancement is not due to a bulk property of unmodified cometary dust grains. The most probable source of submicron particles is the breakup of large agglomerates of small (~1000 A) spherical particles like those found by particle collection experiments.