Welcome to brain Stuff from house stuff works dot com where smart happens. Hi Am Marshall Brain with today's question, is there an easy way to understand how time zones work? In January, people have a special interest in time zones. That's because the shouting of Happy New Year happens at midnight in your local time zone. Meanwhile, other time zones either have already celebrated the new year or they're sitting
around waiting to do it. So cities in New Zealand celebrate New Year's Day first, followed by cities in Japan, Australia, Russia, China, and India, followed by cities in Europe and Africa, followed by cities in North and South America, and then ending on islands out in the Pacific Ocean like Hawaii and finally Samoa. There are four separate time zones, so there are twenty four separate times when balls drop, Happy New Year, gets shouted, and people engage in flagrant public displays of
affection and intoxication. So let's start at the beginning. Why do we have time zones? Keep in mind that there's another way we could do this. We could have a single time that holds true all over the planet. When it's noon in Moscow, it could also be noon in London, New York, and Los Angeles. The problem is that people really don't like that. People much prefer for it to be noon when the sun reaches its peak in the sky.
In order for it to be noon when the sun reaches its peak, everybody needs to set their time according to the sun. And this is how things used to be. It used to be that there were no clocks. People use things like sun dials. Then there were clocks, but only the rich people could afford them because they were really expensive. So a town would have a central clock tower with bells loud enough to be heard all over town, and the clock keeper would set the clock according to
the sun. This system worked well until trains started to move quickly from town to town. In order to run a punctual train schedule, all the towns needed to have a coordinated time system rather than setting their clocks loosely according to the sun zenith. So the idea of time
zones was created to help keep people from missing their trains. Today, the world has twenty four time zones, with all the clocks in the same time zone displaying the same time, but it can still be confusing, especially if you're trying to schedule a phone call with someone in China or Australia. How do you make sense of this? The easiest way is to get out a globe and a table lamp. The table lamp represents the sun position your globe, so that England is pointing toward the sun. In this model,
it's now high noon in England. For historical reasons, the zero degree longitude line runs through Greenwich, England. This is called the prime meridian, and this place on the globe is also known as GMT plus zero or a Greenwich meantime or UTC plus zero, where UTC stands for coordinated Universal Time. So look at your globe looking down at the north pole. Imagine the globe divided into twenty four pie shaped slices. Each slice is a time zone. It's
high noon in the England time zone. From the vantage point of the North Pole. The Earth spins counterclockwise. That's why the sun rises in the east and sets in the west. In the slice immediately adjacent to England on the left, it's one PM or UTC plus one. In the slice immediately adjacent to England on the right, it's eleven am or UTC minus one. As the Earth rotates counterclockwise. In one hour, it will become high noon in the
slice immediately adjacent to England on the right. Five hours after its high noon in England, the Earth will have rotated enough for it to be high noon on the East coast of the United States. This is referred to as U t C minus five. The central time zone of the U S is ut C minus six, Mountain and Pacific are U t C minus seven and UTC minus eight, respectively. Hawaii is U t C minus ten, and finally Samoa is U t C minus eleven. The International date Line is on the opposite side of the
globe from England, over near New Zealand. This first time zone is ut C plus twelve. This is the first time zone to see January one. Each new day starts in the time zone adjacent to the International date Line twelve hours before it's midnight in England, it's midnight in Auckland, New Zealand, eleven hours after it's midnight in England, and it's midnight in Samoa. Then the Earth rotates past the International dateline. It becomes January second in New England, and
the cycle repeats. When you imagine how the globe rotates with respect to the Sun like this, it's easy to keep track of the time zones. Be sure to check out our new video podcast, Stuff from the Future. Join How Stuff Work staff as we explore the most promising and perplexing possibilities of tomorrow. The How Stuff Works I Fine app has arrived. Download it today on iTunes.