TIME ZONES

TIME ZONES Why do we have time zones? How many time zones are there around the globe? How wide is each time zone? What happens to the time if you travel 1 time zone west or east? How many time zones are there in the US? What happens when you cross the international dateline?

Earth rotates west to east Solar time is based on the position of the sun NIGHT IS FALLING ON EARTH Look at the East Coast of the United States. The lights are already lit. California the sun is still visible.

This pictures shows AMERICAN CITIES at night.

THERE IS A 1 HOUR TIME DIFFERENCE FOR EVERY 15° OF LONGITUDE LONGITUDE AND TIME The world rotates (spins) 360° in 24 hours. 360° / 24 hours = 15° per hour The world has 24 time zones, Each time zone is l5° apart. THERE IS A 1 HOUR TIME DIFFERENCE FOR EVERY 15° OF LONGITUDE

The Prime Meridian (Greenwich, England) is the starting point for time zones The world rotates west to east (counterclockwise), so time zones to the east are ahead of time zones to the west

EAST INCREASE Time is forward to all places to the east WEST LESS Time is backward to all places to the west

East Increase – West Less (1 hr per l5°) If it 9 p.m. at Position D, what time is it at position C? Position B? If it is 1 p.m. at Position X, at which location is the time 5 p.m.

INTERNATIONAL DATELINE 180° SEPARATES 2 CALENDAR DAYS. EAST to WEST – gain a day WEST to EAST – lose a day TUESDAY MONDAY If you took a cruise on a ship, circumventing, or traveling around the entire planet, you would experience firsthand a phenomena that would help you understand the importance of an international dateline. An explorer by the name of Ferdinand Magellan did just that in the year 1519. Magellan along with 241 men set out to travel around the entire Earth. These men kept very careful records as they traveled. Yet, when they returned, they found that their calendars were off by one day with the calendars of everyone in their home countries. What happened? How did these men loose an entire day? The day was not lost all at once. It was lost little by little, as the traveled around the Earth. If you stay in one place, a day lasts 24 hours. However, if you travel the opposite direction of the rotation of the Earth, your day will be slightly longer than 24 hours, because you are traveling ahead of the setting sun. If you travel with the rotation of the Earth, your day will be slightly shorter than 24 hours, because you are traveling into the sunset. At any one moment there are actually two days on the Earth at the same time. A new day begins at midnight on the International Dateline. It travels around the Earth, until 48 hours later it ends back at the International dateline. If you were to travel across the International Dateline, the date would change either forward, or backward. This line actually lies in the middle of a time zone. This means that the hour on the clock would not change, as you crossed over, just the date.

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PRIME MERIDIAN 0° NOON

Do you get it? QUIZ Explain how to locate Polaris in the night sky. What does the altitude of Polaris tell us? If the altitude of Polaris is increasing, which direction are you traveling? What is the largest angle of latitude? What is the largest angle of longitude? 6) What is the latitude & longitude of Oswego,NY? (in degrees & minutes) 7) It’s 5pm in Burnt Hills, what time is it 45° to the East? 8) If it’s 7am in Greenwich England, what time is it at 30 ° West Longitude.