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 some, all the quarter phases of the Moon and their calendar dates during 2022 can be found in this well-planned array of telephoto images. Of course, you can observe a first quarter Moon tonight.

International: Observe the Moon Night

Tomorrow’s picture: ghostly northern lights

弦月
影像提供与版权: Marcella Giulia Pace

说明: 介于新月与满月中间的月相，称为上弦月。在月球每个月绕行地球一圈的轨道上，此时走了4分之1程。在上弦月之时，可见到月亮的可见表面之半，虽然整个可见的半面其实都受到阳光的照耀。而在满月和新月中间的月相，则是下弦月，此时能看到另一半的可见月表。于上弦月与下弦月时，分隔月亮黑夜与白昼的明暗交界线，恰好正中分割了月面。此时在明暗交界线附近的月坑和山峰，都曳着长长的影子，因此凹凸分明，是观测月亮的好时机。如果你错过了2022年的部分弦月，可以在这张精心规划的长焦镜头影像里，找到这年的所有弦月和它们发生的日期。今晚算是很凑巧，可再次观赏上弦月。 （quarter moons 弦月）

国际: 观测月夜

明日的图片: ghostly northern lights