(astronomy) a hypothetical huge collection of comets orbiting the sun far beyond the orbit of Pluto; perturbations (as by other stars) can upset a comet's orbit and may send it tumbling toward the sun
(astronomy) a hypothetical huge collection of comets orbiting the sun far beyond the orbit of Pluto; perturbations (as by other stars) can upset a comet''s orbit and may send it tumbling toward the sun