Time Zones

Our planet,the Earth,is the 3rd planet from the sun.

It is a beautiful,rotating sphere.

The side facing the sun is in daylight.

The side facing away from the sun is in darkness.

For example,when it's daytime in the US ,it's nighttime in China.

In fact,there's a 12 hour time difference between Boston and shanghai.

When it's midnight in shanghai.it's noon in Boston.

The Earth rotates from west to east.

To know which direction is east or west,watch the sun.

The sun travels through the sky from east to west.

The sun comes up in the east and goes down in the west.

Again ,this is because the Earth rotates.

It takes 24hours for the Earth to make a complete rotation.

And that is the length of one day.

Because of the Earth 's rotation,the Earth is divided into time zones.

Some countries,such as the Us,have several time zones.

When it's 10am in NewYork.it's 7am in SanFrancisco.

Europe and the US are separated by several time zones.

When it's 5:00pm in Paris,it's 11:00am in Boston.

So there's a six hour difference between Paris and Boston.

One large country,China,has just one time zone for the whole country.

As a result,at the same time,some parts of the country can be dark and other parts can be light.

As you travel around the Earth,the time changes.

The time of day depends on your location on the planet.

When you travel east or west,you may cross several time zones

For example,if you travel from Beijing to Los Angeles,you cross eight tome zones

That means when it's noon on sunday in China,it's 8:00pm on saturday in Los Angeles.

For travelers,this means it can be very difficult to sleep after a long flight

The clock may say 8:00pm,but for your body it's noon

This is called jet lag

Crossing several tome zones causes jet lag.

It depends on how far east or west you travel

Because of the Earth's rotation,theEarth is divided into time zones.