UPSC Prelims 1999 · General Studies
Question 7: Geography
A ship sailing from the eastern extremity of the Aleutian Islands to Dutch Harbour crosses the 180° meridian at 23.30 hrs on January 1, 1999. What time and date will be recorded by the captain of the ship in his diary after one hour journey from the point of crossing of the meridian?
AnswerThe answer is (a).
The 180 degree meridian is, broadly, the International Date Line. Crossing it eastward, you move the calendar back by one day; crossing westward, forward by one day. The ship is heading east to Dutch Harbour, so at the crossing its diary goes from 23.30 on 1 January to 23.30 on 31 December. One hour later, midnight passes and the clock reads 00.30 on 1 January. Remember: eastward across the line you repeat a day.
Why each option is right or wrong
- (a) Right. Crossing east sets the date back a day, so one hour on the diary reads 00.30 on 1 January.
- (b) Wrong. Moving forward to 2 January is what happens crossing the line westward.
- (c) Wrong. Crossing the line never moves the date forward by two days.
- (d) Wrong. Crossing the line never moves the date forward by three days.
Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 1999, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.