弦月
2023年10月21日 Quarter Moons Image Credit & Copyright: Marcella Giulia Pace Explanation: Half way between New Moon and Full Moon is the Moon’s first quarter phase. That’s a quarter of the way around its moonthly orbit. At the first quarter phase, half the Moon’s visible side is illuminated by sunlight. For the Moon’s third quarter phase, half way between Full Moon and New Moon, sunlight illuminates the other half of the visible lunar disk. At both first and third quarter phases, the terminator, or shadow line separating the lunar night and day, runs down the middle. Near the terminator, long shadows bring lunar craters and mountains in to sharp relief, making the quarter phases a good time to observe the Moon. But in case you missed…