We might expect it to have a very faint blue coloured sky, but due to the haze of dust that remains suspended in the air the daytime sky on Mars appears more yellow. The low density of air molecules means that the Rayleigh scattering that causes our skies to be blue on Earth has a very small effect on Mars. Mars’s atmosphere is much thinner than the Earth’s - less than one per cent. Other planets don’t have an atmosphere exactly like ours, and so their skies would look different. Hence the Sun and skies look redder at dawn and dusk. Instead we see the red and orange light that travels towards us since this light hasn’t been scattered very much. When the Sun is low in the sky, the light has to travel a longer distance through the Earth’s atmosphere so we don’t see the blue light because it gets scattered away. Small air molecules in the Earth’s atmosphere scatter the sunlight during the day to give us a blue coloured sky Why does the sky look red during sunrise and sunset?ĭuring sunrise or sunset, the sky appears to change colour. It’s because our eyes are actually more sensitive to detecting blue light, and more of the sunlight coming into the Earth’s atmosphere is blue rather than violet. In reality, violet light has a shorter wavelength compared to blue light and therefore it’s scattered more – so why isn’t the sky violet? It’s redirected into many different directions all over the sky, whereas the other wavelengths aren’t scattered as much. This is because the light travels a shorter distance through the atmosphere to get to us it’s scattered very little, even the blue light.ĭuring the day the sky looks blue because it’s the blue light that gets scattered the most. The sky during the dayĪt noon, when the Sun is overhead it appears white. This type of scattering increases as the wavelength of light decreases, so blue light is scattered more than red light by the tiny air molecules in our atmosphere. The type of scattering that occurs is known as Rayleigh scattering named after Lord Rayleigh (John William Strutt) who discovered it. The size of these molecules is much smaller than the wavelengths of visible light. Sunlight can be redirected by the air molecules and this is known as 'scattering'. The Earth’s atmosphere is composed of lots of different air molecules.
Violet and blue light have the shortest wavelengths and red light has the longest.įind more astronomy videos and resources How is light scattered? These different colours have different wavelengths, and this affects how they interact with different substances.
This experiment demonstrates that white light is composed of all the colours of visible light in roughly the same amounts.
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