That's probably why I keep getting questions like these on my blog: Frequent international travelers are comfortable with the IDL. They're used to the idea of changing the day and date, yet even they would struggle with most of those questions. The lyrics from that classic song come to mind: "Does anybody really know what time it is? " As you will soon discover, the answer to both questions is "yes." There are no equations, but you might encounter a few new terms.
If someone was 45° away from Greenwich, he or she would experience a three-hour time difference; 45° to the west would mean that the person was in Coordinated Universal Time (UTC) -3, while someone 45° to the east would be in UTC 3.And the countries on western side of it (Alaska/Hawaii and other areas) have the time zone 9–12 hours less than Greenwich.So when travelling across the line, one's watch has to be adjusted 20–24 hours, depending on the time zones.International convention accepts the line as the location where one day is divided from the next, with the area in the Eastern Hemisphere one day ahead of the Western Hemisphere.This line is necessary to address certain oddities that occur during travel; people going all the way around the world perceive themselves either gaining or losing a day, depending on which direction they traveled in.People relied on the definition that "noon" was when the Sun was highest in the sky, and due south.