inwardly they would be reflected between the interior and exterior surfaces 72 and 74 until they are eventually absorbed by the material fig8 illustrates the performance of the skylight dome when the sun is relatively low in the sky specifically the direct sunlight rays 150 arrive at the skylight dome 20 only slightly inclined from the horizontal the direct rays 150 pass directly through the non prismatic portion 84 without the prismatic portion 82 of the present invention the direct rays 150 would continue to pass through the skylight dome 20 so that none of those rays 150 would pass downwardly into the tube assembly 16 instead the prismatic portion 82 reflects the direct rays 150 downwardly through the dome 20 at a variety of angles the reflected rays 150 39 are illustrated as dashed lines and pass downwardly at a variety of reflected angles as seen more easily in fig9 the light rays 150 34 slightly inclined from the horizontal may also pass through the interior surface 72 and become trapped between the interior and exterior surfaces 72 and 74 similarly to the light rays 150 34 seen in fig6 7 however these rays 150 34 also descend through the interior 75 of the rear face 80 and eventually exit from the interior 75 through the offset lower edge 95 and into the tube assembly 16 additionally these rays 150 34 then have a more centrally located reflection angle allowing for fewer reflections as they descend the tube assembly 16 the object of the present invention is to increase the amount of light which reaches the diffuser 30 by allowing rays 150 trapped within.