If the earth’s direction of rotation is reversed, what should be the IST when it is noon at the International Date Line ?
✓ Correct answer: c) 18.30 hrs
ExplanationIndian Standard Time (IST) is UTC +5:30 hours, based on the longitude 82°30’ E.The International Date Line (IDL) is at approximately 180° longitude.The difference in longitude between the IDL (180°) and the IST meridian (82°30’ E) is 97°30’ (180° – 82°30’).Time difference calculation :15° of longitude corresponds to 1 hour of time difference.97°30’ corresponds to 6 hours and 30 minutes (97.5° ÷ 15° = 6.5 hours).Normal Earth Rotation (West to East) :When it is 12:00 noon at the IDL, it would be 05:30 AM (IST) (because IST is ahead of IDL by 6 hours 30 minutes).Reversed Rotation (East to West) : If the Earth rotates in the opposite direction, the time difference reverses.Instead of being ahead, IST will lag behind the IDL by 6 hours and 30 minutes.When it is 12:00 noon at the IDL, it will be 6:30 PM (18:30 IST).494
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