Have you ever wondered why the sky is blue during the day, but turns red and orange during sunrise and sunset? And if space is dark, why isn’t the sky always black? The answer lies in the way light interacts with the Earth’s atmosphere.
When sunlight enters the Earth’s atmosphere, it is scattered in all directions by the molecules and particles in the air. This scattering is known as Rayleigh scattering, named after the British scientist Lord Rayleigh who first described it in the 19th century. The shorter wavelengths of light, such as blue and violet, are scattered more than the longer wavelengths, such as red and orange. This is why the sky appears blue during the day, as the blue light is scattered in all directions and reaches our eyes from all parts of the sky.
During sunrise and sunset, the light has to travel through more of the Earth’s atmosphere to reach our eyes. This means that more of the blue and violet light is scattered away, leaving only the longer wavelengths of red and orange to reach our eyes. This is why the sky appears red and orange during these times.
But why isn’t the sky always black, if space is dark? Even though space is dark, it is not a perfect vacuum. There are still some particles and molecules in space, and these can scatter light just like the Earth’s atmosphere. However, the scattering in space is much weaker than in the Earth’s atmosphere, so the sky appears black most of the time.
In conclusion, the reason why the sky is blue during the day and red during sunrise and sunset is due to the way light is scattered by the Earth’s atmosphere. And even though space is dark, there are still some particles and molecules that can scatter light, but the scattering is much weaker than in the Earth’s atmosphere.
