Science (086) — AI-generated practice question

The sky appears blue due to scattering of light. The atmosphere contains fine particles (air molecules, dust, etc.) whose size is smaller than the wavelength of visible light. These particles scatter shorter wavelengths (blue light) much more strongly than longer wavelengths (red light). This scattered blue light reaches our eyes from all directions, making the sky appear blue.

At very high altitudes, the atmosphere is extremely thin and there are very few scattering particles. Since scattering is not prominent at such heights, the sky appears dark to astronauts.

Source: Chapter 10, Section 10.6.2 — Why is the colour of the clear Sky Blue?

---

• Two parts needed (split marks ~2+1): Explain scattering causing blue sky, then explain why it's dark at high altitude.
• Key phrase to use: "scattering of blue light (shorter wavelength) is more than red light (longer wavelength)."
• The astronaut answer is direct from the textbook: "The sky appears dark to passengers flying at very high altitudes, as scattering is not prominent at such heights." Quote or paraphrase this line — examiners look for it specifically.
• Avoid over-explaining Tyndall effect here; it's not directly asked.