OE

The first blank describes what the Moon does to the Sun; the second sentence tells you that the Moon’s shadow is caused by blocking the sun, so you are looking for a word that means blocks. Of the choices, only occludes means blocks; secularizes means separates from religious connection and epitomizes means typifies. The second blank describes the occurrence, and the clue is in the first line of the passage: one of the rarest of celestial events. Therefore, you need a word that means rare. Of the choices, only atypical means rare; desultory means random, but not necessarily rare, and momentous means of far-reaching importance.