3. A full Moon will be observed from Earth when the Moon is located in which of the positions shown in the preceding figure? (Position 1: between Sun and Earth; Position 2: first quarter; Position 3: opposite Sun; Position 4: third quarter)
Answer: C
A full Moon occurs when the Moon is positioned opposite the Sun.
A full Moon will be observed from Earth when the Moon is in Position 3, which is opposite the Sun. This alignment allows the entire illuminated side of the Moon to be visible from Earth.
A) 1
Position 1 places the Moon between the Sun and Earth, which results in a new Moon phase, not a full Moon. In this position, the side of the Moon facing Earth is not illuminated, so it would not be visible at all.
B) 2
Position 2 corresponds to the first quarter phase of the Moon, where only half of the Moon's surface is illuminated as viewed from Earth. This phase does not provide a full view of the Moon, as it is not yet opposite the Sun.
C) 3
Position 3 represents the full Moon phase, where the Moon is located directly opposite the Sun. In this configuration, the entire face of the Moon is illuminated and fully visible from Earth, making this the correct answer.
D) 4
Position 4 indicates the third quarter phase of the Moon, where again only half of the Moon is illuminated. The Moon is not opposite the Sun in this position, hence it cannot be considered a full Moon.
Conclusion
Position 3 is definitively the correct choice, as it is the only configuration that allows for the full illumination of the Moon when viewed from Earth. All other positions fail to provide the complete view necessary for a full Moon, highlighting the importance of the Moon's alignment relative to the Earth and Sun in determining its phases.