Read the following statements carefully and select the correct option.…
2024
Read the following statements carefully and select the correct option.
Assertion (A): The stars in the night sky appear to move from east to west.
Reason (R): The earth rotates from west to east.
- A.
(A) and (R) are both correct and (R) is the correct explanation for (A).
- B.
(A) and (R) are both correct but (R) is not the correct explanation for (A).
- C.
(A) is correct but (R) is incorrect.
- D.
(A) and (R) are both incorrect.
Show answer & explanation
Correct answer: A
In any Assertion-Reason item, the Assertion and the Reason must each be checked for truth on their own, and only then is it checked whether the Reason is the actual cause of the Assertion. For the daily (diurnal) motion of celestial objects, the general rule is: any real rotation of the observer's own reference frame makes all external, effectively fixed objects appear to rotate in the opposite sense across the sky.
Applying this here: Earth genuinely spins on its own axis from west to east. Because an observer on the ground is rotating along with the Earth in that direction, the stars — which are essentially fixed relative to the Earth's motion — appear, from the ground, to trace the opposite path, drifting from east to west over the course of a night. So the physical mechanism named in the Reason is exactly what produces the effect described in the Assertion.
This is confirmed by the everyday observation of the Sun: for the same reason — Earth's west-to-east spin — the Sun (and Moon) are seen to rise in the east and set in the west, the same east-to-west apparent drift pattern. Both independent observations line up with a single underlying cause, Earth's rotation direction.
Hence both statements are factually correct, and the second statement is the direct physical explanation for the first.