Which phase shows a half-illuminated Moon with the left side lit?

Which phase shows a half-illuminated Moon with the left side lit?

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

Answer: (B)

Moon phases show how much of the Moon’s sunlit side we see from Earth. When the Moon is exactly half illuminated, that’s a quarter Moon. The side that’s lit tells you which quarter it is. If the lit portion is on the right, it’s the first quarter; if the lit portion is on the left, it’s the third (last) quarter. So a half-illuminated Moon with the left side lit corresponds to the third quarter phase, typically about three weeks after the New Moon (about a week after the Full Moon). Note that in the Southern Hemisphere the orientation appears reversed, but for most Northern Hemisphere observers, left-lit means third quarter.

Moon phases show how much of the Moon’s sunlit side we see from Earth. When the Moon is exactly half illuminated, that’s a quarter Moon. The side that’s lit tells you which quarter it is. If the lit portion is on the right, it’s the first quarter; if the lit portion is on the left, it’s the third (last) quarter. So a half-illuminated Moon with the left side lit corresponds to the third quarter phase, typically about three weeks after the New Moon (about a week after the Full Moon). Note that in the Southern Hemisphere the orientation appears reversed, but for most Northern Hemisphere observers, left-lit means third quarter.