Final answer:
Traveling across the International Date Line from east to west, you would land on the previous day due to the timekeeping conventions established by the line's position at the 180° meridian. This ensures global time consistency.
Step-by-step explanation:
When you travel across the International Date Line from east to west, you would land in the previous day. This is because the International Date Line serves as the imaginary boundary where the date changes by one day when it is crossed. It is roughly aligned with the 180° meridian of longitude, running down the middle of the Pacific Ocean and zigzagging to avoid splitting landmasses. Since the concept of time and time zones is based on the rotation of the earth and its division into 24 longitudinal sections, timekeeping becomes complex when one travels across this line.
For instance, if it is midnight at the International Date Line and you move westward, it would then technically be 11 p.m. the previous day. Travel for a full 24-hour cycle, crossing all time zones, and when you return to your original position, it should be the same time, but it would be the previous day because you’ve essentially traveled back in time by crossing the date line. This seemingly paradoxical switch is necessary to maintain a consistent and rational system of timekeeping across the globe.
An example to illustrate this is the attack on Pearl Harbor, which occurred on December 7, 1941, according to the United States, but due to the difference in dates caused by the International Date Line, it is recorded as December 8, 1941, in Japan. Thus, crossing the International Date Line from east to west, you must set your watch back 24 hours, effectively moving to the previous day of the week.