This means that different parts of the planet receive the sun's direct rays at different times, so when it is noon on one part of Earth — the period when the sun is at its highest in the sky — another part of the planet may be completely in shadow or experiencing sunrise or sunset.
But humans don't travel at such speeds unless you are on the International Space Station , and when not traveling people generally stay in one place. So, to allow people to experience daylight hours in roughly the same amount — that is, to experience a normal day from sunrise to sunset — time zones are in use around the world.
The first system of time zones was proposed by Sir Sandford Fleming in , according to an article in Globe and Mail , a Canadian news publication.
Fleming was a Scottish engineer who helped design the Canadian railway system. He wanted to make the railroad more efficient and avoid any complications resulting from the different schedules set by the different train stations, which set the time according to their local astronomical conditions, according to Encyclopedia Britannica.
Accordingly, he proposed a system of 24 standard time zones that would span the circumference of the Earth. Within each time zone, all clocks would be set to an average time that best represented where the sun was located in the sky. The practicality of his system soon caught on, so that by most of the industrialized nations of the world had adopted it. Today, with a number of significant modifications, we still use the time-zone system originally proposed by Fleming. The logic of dividing Earth into 24 zones is derived from the fact that the planet is a sphere, and like any sphere it can be divided into equal sections, or degrees.
Each time zone is measured as 15 degrees wide, and divided by 15 is All of these zones are numbered consecutively eastward from what is called the prime meridian, which is a line of longitude that runs directly through the British Royal Observatory in Greenwich, in the United Kingdom. The prime meridian was established in at a time when the U. With a powerful navy, the British were well advanced in navigation and timekeeping and were using the most sophisticated devices available to reckon global position and time.
The prime meridian, at 0 degrees longitude, is the point from which all other measurements of longitude are taken. As you go east from the prime meridian, the time zones increase consecutively by one hour, or conversely, decrease consecutively by one hour as you go west. But Earth, of course, does not go on indefinitely; eventually, a point is reached when you have to start over — or jump backward or forward in time depending on your direction of travel.
London, U. Going eastward from San Francisco to London, you move ahead eight time zones, which really means you skip forward eight hours. So, when the time in San Francisco is 1 p. However, if you were to move eight time zones in the opposite direction from San Francisco at 1 p. It's not simply a matter of subtracting eight hours from the San Francisco time. You start by subtracting an hour for each time zone moving west, making it to a. Now you have to add a full 24 hours to your calculations and jump a full day ahead, making it 9 a.
But you're not done yet. Are you worried or stressed? Click here for Expert Advice. Comment 0. Post Comment. Disclaimer: Comments will be moderated by Jagranjosh editorial team.
Comments that are abusive, personal, incendiary or irrelevant will not be published. Please use a genuine email ID and provide your name, to avoid rejection. This website uses cookie or similar technologies, to enhance your browsing experience and provide personalised recommendations.
By continuing to use our website, you agree to our Privacy Policy and Cookie Policy. Depending on which time zone the country follows, the time difference on either side of the line is not always 24 hours.
For example, if you travel the km mi across the date line from Baker Island to Tokelau , you must add 25 hours, or 1 day and 1 hour. Every day between and UTC , three different calendar dates are in use simultaneously on Earth.
Check our Time Zone Converter!
0コメント