Why is the sky blue in the day, yet it becomes dyed bright red at sunset? The reason is that the atmosphere splits white light into the colours of the rainbow like a prism. Short-wavelength colours such as blue and green tend to scatter more, making the sky blue usually. But as the sun sets, the angle at which sunlight enters the atmosphere changes and the light has to travel through more atmosphere before hitting Earth. The more the light travels, the more it scatters and blue-green light is scattered so much that it can no longer be seen. At this stage, the dominant remaining colour are orange and red, which have longer wavelengths.
But this alone would only give the sky a dull red colour. The brilliant splash of red and orange across the sky every evening is thanks to the scattering of light in a certain way by cloud droplets and other particles. This is why an exceptionally bright orange sunset can suggest rain the following day.
A “perfect” sunset requires the alignment of various factors such as the angle of the sun (affected by time and season), humidity, temperature, air component and the surrounding landscape. Depending on these factors, the sunset can range in colour from a deep red to a bright orange, to a pastel yellow to baby pink or purple (or at worst, a piddly dull yellow light). This means that a perfect sunset tends to only happen at a single moment in time when these factors align to your preference.
The corollary to this is that a perfect sunset is always a fleeting moment. No matter how much you want to hold on to it, time marches on and the sunset slowly fades away. It is futile to stop the moment from passing – to cling to the beauty of the moment. All you can do is enjoy that single moment while you can. It is a time when the past day comes to a close, while the future is getting ready to start. In that moment, do not think about the past or the future – just focus on the present. Take in the brilliant colours with your eyes. Listen to the chirping of the birds returning home. Feel the cool breeze brush past you. When the sun finally sets, despair not the passing of the beautiful moment, but cherish the fact that you had such a great moment. Because as you know, another sunset awaits you tomorrow.
