Question

You notice the Moon low in the eastern sky at sunrise. Its phase must be:

A) waxing crescent
B) waxing gibbous
C) full
D) waning gibbous
E) waning crescent

Answer 1

Option D). The Moon phase noticed low in the eastern sky at sunrise would be a waning gibbous, which occurs after the full Moon phase as the Moon's illumination begins to decrease.

Step-by-step explanation:

At sunrise, the Moon must be in waning gibbous phase if it is low in the eastern sky. This is due to the fact that the full Moon rises at sunset and sets at sunrise, exactly opposite the Sun in the sky. Following the full Moon, the Moon moves into its waning phases, during which time its apparent size begins to decrease but it is still largely illuminated. Every night, the Moon rises later due to its eastward orbit. Waning gibbous is the right response because it would be visible at sunrise when the Moon is low in the eastern sky, following the full moon phase.