The Moon is Earth’s companion in space. It’s a night- sky object that’s hard to miss as it reflects sunlight from its grey and barren soil, shining white like a battery-operated torch on the blooming and fertile soils of our planet. That’s until it begins to turn red.
You might have seen a so-called blood Moon before, as the lunar surface gradually shifts through progressive shades of crimson. Scientifically this is called a total lunar eclipse and it’s the positioning of the Sun, our planet and the Moon that’s responsible for the eye-catching difference in colour.
To imagine what happens during one of these events, picture the Sun, Earth and Moon in a line and in that order. Remember that, given our lunar companion is much smaller than Earth, any great amount of light trying to reach it from our star will be blocked out by our planet’s bulk. This means our natural satellite is forced to remain in its shadow. However, not all rays of light are deterred by the lineup – a few manage to sneak through to beam onto the lunar land.
This visible light, made of a spectrum of different wavelengths, has battled its way through Earth’s atmosphere. It doesn’t get through unscathed – most of the blue light is filtered out and deep-red or orange rays of light are left that are much dimmer.
With Earth’s atmosphere toying with some of the visible light by bending or refracting it, a small band of longer wavelength red makes its way to the lunar surface, painting our companion crimson.
Image Credit: Juan lacruz