(B) The colour of clear sky from the earth appears blue but from the space it appears black. Why ?
Generated by claude-sonnet-4-6 · 2026-06-15 06:52 · grounding rag
Model Answer
From Earth, sunlight passes through the atmosphere where fine particles and air molecules scatter blue light (shorter wavelength) more strongly. This scattered blue light reaches our eyes, making the sky appear blue.
From space, there is no atmosphere to scatter sunlight. In the absence of scattering, the sky appears black.
Source: Chapter 10, Section 10.6.2 – Why is the colour of the clear Sky Blue?
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Explanation
- The key concept is scattering of light — fine atmospheric particles scatter shorter wavelengths (blue) more effectively.
- Two contrasting situations are asked: from Earth (atmosphere present → scattering → blue) and from space (no atmosphere → no scattering → black/dark).
- The passage directly states: "If the earth had no atmosphere, there would not have been any scattering. Then, the sky would have looked dark."
- Always mention shorter wavelength to justify why blue is scattered more — this earns the second mark.