BrainiLab Academy · Science & nature
Blue skies and red sunsets
Discover why the sky is blue and sunsets turn red. Two short science lessons connect everyday sky colours to the journey of sunlight.
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What you’ll explore
A blue afternoon becomes an orange evening. What changed?
Start with the colours hidden in sunlight, then follow its longer path through the evening air. These two short lessons fit together; read at your own pace and try the optional quizzes.
One discovery at a time
Your lessons, step by step
- 1
Read →2 min read · Quick quiz
Why is the sky blue?
Connect the blue daytime sky to sunlight scattered by air molecules.
Ready when you are - 2
Read →2 min read · Quick quiz
Why are sunsets red?
Explain how the low Sun’s longer air path changes the colours reaching us.
Ready when you are
A few words worth knowing
- Atmosphere
- The layer of gases around Earth.
- Scattering
- Light being redirected in different directions.
- Wavelength
- The distance from one wave peak to the next.
- Rayleigh scattering
- Scattering by very small particles such as air molecules, which redirects shorter wavelengths more strongly.
Curious to dig deeper?
- NASA Space Place — Why is the sky blue?
- Met Office — Why the sky is blue and sunsets red
- NOAA NESDIS — Sunlight, wavelengths and sky colour
- Royal Observatory Greenwich — Why is the sky blue?
Follow the sources, explore a little further, or tell us if something needs a correction. Suggest a correction.