Q 01/05

Through which ocean does the International Date Line run?

A) Pacific

B) Atlantic

C) Indian

D) Arctic

Answer · why

A) Pacific

It roughly follows the 180° meridian, halfway round the world from Greenwich, bending around islands and territories.

Q 02/05

Which line of longitude does the International Date Line roughly follow?

A) 90°

B) 120°

C) 180°

D) 150°

Answer · why

C) 180°

It sits opposite the IERS Reference Meridian, the successor to the Greenwich prime meridian.

Q 03/05

What happens to the calendar date when you cross the date line travelling eastbound?

A) It goes forward one day

B) It stays the same

C) It goes back one hour

D) It goes back one day

Answer · why

D) It goes back one day

Westbound travellers do the reverse and jump forward a day.

Q 04/05

Is the International Date Line fixed by international law?

A) Yes, by a UN resolution

B) No, it is a cartographic convention

C) Yes, by the 1884 Meridian Conference

D) Yes, by maritime treaty

Answer · why

B) No, it is a cartographic convention

That is why countries through whose waters it passes have been able to move it for their own convenience.

Q 05/05

Travelling westward around the world, how must you set your clock for every 15° of longitude crossed?

A) Back one hour

B) Forward one hour

C) Forward 15 minutes

D) Back 24 hours

Answer · why

A) Back one hour

Then, at the date line, the clock jumps forward 24 hours to make up for it.