The correct option is A is false but R is true
Explanation
The color of the sky as perceived by an observer depends on the scattering of light. This phenomenon occurs when sunlight interacts with particles in a medium (such as the atmosphere), causing light rays to deviate from their straight path. The specific color observed depends on the wavelength of light scattered, which is influenced by the size of the particles (Rayleigh scattering).
Statement-wise Analysis
- Assertion (A): Incorrect. To an astronaut in space, the sky appears black, not blue. The blue color seen from the Earth's surface is due to the scattering of shorter wavelengths (blue and violet) by the gas molecules in the Earth's atmosphere. Since space is a near-vacuum, this scattering does not occur.
- Reason (R): Correct. Scattering of light requires the presence of material particles (atoms, molecules, or dust) to interact with electromagnetic waves. In the absence of an atmosphere (vacuum), there are no particles to scatter the light. Consequently, light travels in a straight line from the source without deviation, leaving the surrounding space dark.
Key Takeaway
The blue color of the sky is a result of the scattering of sunlight by the atmosphere. In the absence of an atmosphere, such as in outer space, no scattering takes place, resulting in a black sky.