第2956期:Shapes and colours of the Moon

You may have heard of the idiom 'once in a blue moon' to describe an event that doesn't happen often. But can the Moon really be blue? Our closest neighbour in this vast galaxy, the Moon, orbits the Earth like a natural satellite. Unlike many of the other planets in our Solar System, ours only has the one moon. If you flew to it, you would land on grey rocks. This is because the lunar surface is made from mostly magnesium, iron and other minerals of that colour. But, if you're lucky to have clear skies under the curtain of night, you may be able to admire its luminosity. You might even see that it seems to change shape and hue.您可能听说过“once in a blue Moon”这个成语，用来描述不经常发生的事件。 但月亮真的可以是蓝色的吗？ 在这个广阔的星系中，我们最近的邻居是月球，它像一颗天然卫星一样围绕地球运行。 与太阳系中的许多其他行星不同，我们的行星只有一颗卫星。 如果你飞过去，你会降落在灰色的岩石上。 这是因为月球表面主要由镁、铁和其他该颜色的矿物质组成。 但是，如果您幸运地在夜幕下拥有晴朗的天空，您也许可以欣赏到它的光度。 您甚至可能会看到它的形状和色调似乎发生了变化。

It's important to understand that the Moon reflects light from the Sun as it orbits the Earth, and that light bounces back to the Earth. The position of the Moon, Sun and the Earth determines how much of the Moon we see. The new Moon appears almost invisible in the sky as it is in total darkness. This is the opposite to the full Moon which is completely lit up. There are eight different phases to the lunar cycle between a full Moon and a new Moon, each lasting around 28 days. In fact, the word 'month' takes its root from 'Moon' because it was almost equal to the lunar phases.重要的是要了解，月球绕地球运行时会反射来自太阳的光，然后光会反射回地球。 月球、太阳和地球的位置决定了我们能看到月球的面积。 新月在天空中几乎看不见，因为它处于完全黑暗的环境中。 这与完全照亮的满月相反。 满月和新月之间的月球周期有八个不同的阶段，每个阶段持续约 28 天。 事实上，“月”这个词的根源是“Moon”，因为它几乎等于月相。

The other phases include the crescent, quarter and gibbous phase. Crescent originates from the Latin verb 'crescere', meaning 'to increase', and so it is the phase just before and after a new Moon as it takes a concave shape. The quarter will show half of the Moon. 'Gibbous' gets its root from the Latin term 'gibbus' which applied to the Moon's convex shape. These shapes are determined by the adjectives 'waning', to get smaller, and 'waxing', to get bigger.其他阶段包括新月期、四分之一期和凸月期。 新月起源于拉丁语动词“crescere”，意思是“增加”，因此它是新月前后的阶段，因为它呈凹形。 该四分之一将显示月球的一半。 “Gibbous”一词源自拉丁语“gibbus”，指的是月球的凸面形状。 这些形状由形容词“逐渐变小”和“逐渐变大”来决定。

So now you know how we've named the shapes, what about those mesmerising colours? The light waves that reach our eyes can vary due to the Moon's position on the horizon and pollution. This is known as Rayleigh scattering. When the Moon is low, light travels through the densest part of the atmosphere and shorter waves of blue scatter away. This leaves only the red and orange light waves to reach us. A warmer atmosphere, as well as smoke from wildfire, may increase the scattering effect as well, making the Moon appear less dull in spring and summer. This is why it's more likely for you to look up and see a pink Moon in April, a golden Moon in May and July, and even a red coloured Moon in the month of June.现在您知道我们如何命名这些形状了，那么那些迷人的颜色呢？ 由于月球在地平线上的位置和污染，到达我们眼睛的光波可能会有所不同。 这称为瑞利散射。 当月亮较低时，光线穿过大气层最密集的部分，较短的蓝色波会散射开来。 这样就只剩下红色和橙色光波到达我们这里了。 温暖的大气层以及野火产生的烟雾也可能会增加散射效果，使月球在春季和夏季显得不那么暗淡。 这就是为什么您更有可能在四月抬头看到粉红色的月亮，在五月和七月看到金色的月亮，甚至在六月看到红色的月亮。