Understanding time zones and how they work

Time zones were created because of Earth’s rotation. The sun illuminates the Earth, but only one portion at a time. Since the sun can’t
rise in every part of the world at once, time zones maintain logical order and regulate day and night across the globe.

1. Understanding Time Zones

Time zones were created because of Earth’s rotation. The sun illuminates the Earth, but only one portion at a time. Since the sun can’t
rise in every part of the world at once, time zones maintain logical order and regulate day and night across the globe.

Imagine if the entire Earth had a single time zone. Noon would be the middle of the day in some places, but it would be morning,
evening, and the middle of the night in others. Since different parts of Earth enter and exit daylight at different times, we need different
time zones.

Having different time zones means that no matter where you live on the planet, your noon is the middle of the day when the sun is
highest, while midnight is the middle of the night. Without time zones, we might have sunrise at 3 o’clock in the morning!
Time zones typically follow longitude, but sometimes they can be a matter of convenience. During the warmer months, most countries
observe Daylight Saving Time (DST), pushing the clock forward an hour to take advantage of additional sunlight.

As Earth rotates on its axis, it moves about 15 degrees every 60 minutes. After 24 hours, it has completed a full rotation of 360 degrees.
The scientists used this information to divide the planet into 24 sections or time zones. Each time zone is 15 degrees of longitude
wide.

The time at Greenwich is called Greenwich Mean Time (GMT). As you move west from Greenwich, every 15-degree section or time
zone is an hour earlier than GMT, while each time zone to the east is an hour later. The international date line stretches between 2
poles and nominally separates one day from another. At the moment midnight arrives on the date line, noon comes to the opposite
Greenwich meridian. To the east from the date line, a new day has already begun, but to the west, it hasn’t yet ended.