Which phase is seen when the illuminated portion is one quarter of the Moon's disk?

Which phase is seen when the illuminated portion is one quarter of the Moon's disk?

• A. New Moon
• B. First Quarter
• C. Full Moon
• D. Third Quarter

Answer: (B)

As the Moon orbits Earth, the portion that is illuminated by the Sun visible from Earth changes, creating the Moon’s phases. The halfway point in the cycle—about a quarter of the way from New Moon toward Full Moon—produces a phase where roughly half of the Moon’s disk is lit. This is the First Quarter, which is why it’s the correct choice: it represents the mid-point of the cycle with the near side showing a half-moon. In the Northern Hemisphere, you’ll see the right half illuminated at this phase. The other options correspond to 0% illumination (New Moon), 100% illumination (Full Moon), and the opposite half-lit at the three-quarter point (Third Quarter).

As the Moon orbits Earth, the portion that is illuminated by the Sun visible from Earth changes, creating the Moon’s phases. The halfway point in the cycle—about a quarter of the way from New Moon toward Full Moon—produces a phase where roughly half of the Moon’s disk is lit. This is the First Quarter, which is why it’s the correct choice: it represents the mid-point of the cycle with the near side showing a half-moon. In the Northern Hemisphere, you’ll see the right half illuminated at this phase. The other options correspond to 0% illumination (New Moon), 100% illumination (Full Moon), and the opposite half-lit at the three-quarter point (Third Quarter).