Longitude and Latitude Info and Activities

Longitude and Latitude info and activities

How Time and Longitude are Related
In order to use the GMT clues to help you ESTIMATE the approximate longitude of a Mystery Class, you must first understand a little background about the relationship between time and longitude. Think about this: In order for sunrise to occur everyplace on earth each day, the earth must spin 360 degrees every 24 hours. If you hold your globe with the North Pole on top, you can see that the vertical longitude lines (called "meridians") add up to 360 degrees. Using the following equation, you can figure out how many degrees the earth turns in each hour:
360 degrees divided by 24 hours = 15 degrees per hour.
Using a division equation again, you can also figure out how many minutes it takes for the earth to spin 1 degree:
60 minutes divided by 15 degrees = 4 minutes per degree.

Why Greenwich Mean Time is Important
Greenwich Mean Time (GMT) is an international time-keeping standard, based on the local time at the 0 longitude point in Greenwich, England. Using GMT, you have an important clue to the approximate longitude location of your Mystery Classrooms.
Each Mystery class has revealed what time it will be using Greenwich Mean Time (GMT) when the sun rises at their Mystery site on March 20, 2001 (the Vernal Equinox.) By knowing this GMT sunrise time for a Mystery Class and also knowing the time the sun rises at Greenwich that day, you can figure out how long the earth spins between the time the sun rises at the Mystery Class location and the time it rises at Greenwich. Once you know this, you can estimate the approximate longitude of each Mystery Class location.
The GMT Worksheet below will walk you through the calculations. We also provide you with two examples where we show you how to calculate the approximate longitude for two of this year's Mystery sites.
Now It's Your Turn!
So let's get started by having you go to the GMT Worksheet. This will give you the GMT Sunrise time for the 10 Mystery classes first, and then walk you through two examples. Print it and go. Good Luck!

Mystery Class GMT Worksheet

This Week's Sunrise/Sunset Times
Remember, the secret Mystery sites recorded their times last Monday, the same day you collected your own local sunrise/sunset data.

Journey North Mystery Class

Sunrise/Sunset Data

Data For: Monday, March 12, 2001

MYSTERY CLASS / SUNRISE / SUNSET
#1 / 06:53 / 18:41
#2 / 07:20 / 19:26
#3 / 06:41 / 19:07
#4 / 06:52 / 18:50
#5 / 06:41 / 21:21
#6 / 06:21 / 18:00
#7 / 07:16 / 19:45
#8 / 06:35 / 18:31
#9 / 06:35 / 18:49
#10 / 06:31 / 18:18

Note: Military time is usually expressed without any punctuation. We have used a ":" between the hours and minutes for clarity.)

/ / / /

Mystery Class GMT Worksheet Estimating Approximate Longitude using GMT Sunrise Times on the Spring Equinox

Instructions:
1. Print 10 copies of this GMT Worksheet (one for each secret Mystery site) and use the step-by-step instructions to estimate the approximate longitude of each Mystery Class.

2. In order to use the GMT Worksheet, you will also need to print out the:

Equinox Sunrise Table

3. To help get you started, we've already calculated the approximate longitude for two of this year's Mystery Class sites, using the GMT Worksheet. Be sure to review the two examples below:

GMT Worksheet Example One
GMT Worksheet Example Two

Worksheet

Step # 1
Fill in the GMT sunrise time and date for the Mystery Class. This is the time it is in Greenwich, England when the sun rises at the Mystery Location.
Put in Box A. / BOX A
Step # 2
Fill in the time that the sun rises in Greenwich, England on March 20, the spring Equinox. This year that sunrise time is 06:03A.M.
Put in Box B. / BOX B
06:03 A.M. (3/20)
Step # 3
Figure out how many hours and minutes there are between the time in Box A and the time in Box B. Put answer in Box C. This is the difference in time between sunrise at Greenwich and sunrise at the Mystery Location. (CAUTION!!! This may not be a simple subtraction or addition equation. Remember that hours and minutes are not in decimal form. Be sure to think about your answer!) Put in Box C. / BOX C
______hours______minutes
Step # 4
For the next step you'll need to convert hours to minutes. Multiply each hour in Box C by 60, add the remaining minutes from Box C.
Put the answer in Box D. / BOX D
______minutes
Step # 5
Almost done! You now know how many minutes the earth spins between the time the sun rises at the Mystery Class location and the time it rises at Greenwich. Since the earth spins 1 degree longitude every 4 minutes, you must next divide by 4 to get the number of approximate longitude degrees away from Greenwich. Divide the number of minutes given in Box D by 4.
Put the answer in Box E. / BOX E
______degrees
Step # 6
Eastern or Western Hemisphere?
To determine the site's longitude you need to know if it is in the Eastern or Western Hemisphere (i.e East or West of Greenwich, which is 0 degrees).

If the sunrise in Box A is laterthan the sunrise in Box B, the Mystery Class is west of Greenwich (Western Hemisphere).
If the sunrise in Box A is earlier than the sunrise in Box B, the Mystery Class is east of Greenwich (Eastern Hemisphere).

/ BOX F
East or West?

Back to Today's Report

Step # 1
Mystery Class #3's sunrise time is given as 09:48(GMT) on March 20. This means it is morning in Greenwich when the sun rises at this site. / BOX A
09:48 A.M. (3/20)
Step # 2
Sunrise time at Greenwich on March 20 is 06:03 A.M. / BOX B
06:03 A.M. (3/20)
Step # 3
The number of hours and minutes between A and B is 3 hours and 45 minutes / BOX C
3 hrs 45 min
Step # 4
Convert the amount of time in Box C into minutes by multiplying the hours by 60 and adding the remaining minutes (3 x 60 = 180 + 45 = 225 minutes) / BOX D
225minutes
Step # 5
Figure out the degrees away from Greenwich by dividing the minutes in Box D by 4 (225 divided by 4 = 56.25 degrees) / BOX E
56.25 degrees
Step # 6
Eastern or Western Hemisphere?
To determine the site's approximate longitude you need to know if it is in the Eastern or Western Hemisphere (i.e East or West of Greenwich, which is 0 degrees). Here, 09:48 A.M. on 3/20 was later than 06:03 A.M. on 3/20, so this longitude location is West. This means the site is west of Greenwich, in the Western Hemisphere. / BOX F
56.25 W

Step # 1
Mystery Class #7's sunrise time is given as 18:24 (GMT) on March 19. This means it is evening in Greenwich when the sun rises at this site. / BOX A
18:24 P.M. (3/19)
Step # 2
Sunrise time at Greenwich on March 20 is 06:03 A.M. / BOX B
06:03 A.M. (3/20)
Step # 3
The number of hours and minutes between A and B is 11 hours and 39 minutes / BOX C
11 hrs. 39 min
Step # 4
Convert the amount of time in Box C into minutes by multiplying the hours by 60 and adding the remaining minutes (11 x 60 = 660 + 39 = 699 minutes) / BOX D
699 minutes
Step # 5
Figure out the degrees away from Greenwich by dividing the minutes in Box D by 4 (699 divided by 4 = 174.75 degrees ) / BOX E
174.75 degrees
Step # 6
Eastern or Western Hemisphere?
To determine the site's approximate longitude you need to know if it is in the Eastern or Western Hemisphere (i.e East or West of Greenwich, which is 0 degrees). Here, 18:24 P.M. on 3/19 was earlier than 06:03 A.M. on 3/20, so this longitude location is East. This means the site is east of Greenwich, in the Eastern Hemisphere. / BOX F
174.75 E