GS PrelimsScience and TechnologyUniverse and Space Technology1996

Consider the following statements: A person in a spaceship located half way between the earth and the sun will notice that the 1. Sky is jet black. 2. Stars do not twinkle. 3. Temperature outside the spaceship is much higher than that on the surface of the earth. Of these statements

A

Only III is correct

B

I and II are correct

C

I and III are correct

D

I, II and III are correct

Correct Answer: Option D

Explanation

1. The question describes a person in a spaceship halfway between the Earth and the Sun. 2. Statement 1: In space, outside the Earth's atmosphere, there are no air molecules to scatter sunlight. Scattering of sunlight by the atmosphere is what makes the sky appear blue on Earth. Without scattering, the sky appears jet black, even when the Sun is visible. (Statement 1 is correct). 3. Statement 2: Stars twinkle when viewed from Earth because their light passes through turbulent layers of the Earth's atmosphere, causing the light path to bend randomly and rapidly. In space, above the atmosphere, starlight travels directly to the observer without atmospheric distortion. Therefore, stars do not twinkle when viewed from space. (Statement 2 is correct). 4. Statement 3: The temperature in space varies drastically. Surfaces directly facing the Sun can become extremely hot, while those in shadow become extremely cold. The ambient temperature of space itself (far from any object) is near absolute zero. While the side of the spaceship facing the Sun would be very hot, the statement 'temperature outside the spaceship' is ambiguous. Furthermore, claiming it's 'much higher than that on the surface of the earth' is questionable. Earth's surface temperatures vary widely, but space presents extremes of both hot and cold, not necessarily always 'much higher'. It's more complex than stated. (Statement 3 is likely incorrect or at least misleadingly simplified). 5. Based on the analysis, statements 1 and 2 are correct.

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