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Mystery Class Reminder: March 15, 2002
Today's Report Includes:
- Spring Begins Wednesday--Happy Vernal Equinox!
- Tips for Success
- The Longitude Problem
- How Time and Longitude are Related
- Why Greenwich Mean Time is Important
- Now It's Your Turn!
- This Week's Sunrise/Sunset Times
- Spring Fever Anyone? Responses to CQ #2
- Clues Calendar
Spring Begins Next Wednesday--Happy Vernal Equinox!
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IMPORTANT: Be sure that you read and follow ALL the instructions in this report very carefully. The special Longitude Clues can help you estimate the approximate longitude for 9 of the 10 secret Mystery Classes. But remember, it's only an estimate, and you'll certainly need to use all the clues that you'll receive in the coming weeks too. (Why do the Longitude Clues help with only 9 of the 10 Mystery Classes? Keep reading to find out.)
We'll also be giving you the latest sunrise and sunset times below, and some of your responses to last week's Challenge Question too.
Everything you need to get started is available in today's report--let's go!
Tips for Success
- Since this Update is packed with information, we suggest you print this report and work from the printed copy. Then, BE SURE to read through all of the instructions carefully and completely, so your longitude estimates are as accurate as possible.
(PLEASE NOTE: For teachers with younger
students (under grade 5), please don't be discouraged by this set of challenging
clues--the clues will be easier after this, and we want you to know that at the end
of the Mystery Class contest, we will group the answers by grade level, so the participants
are grouped with others near their same grade level.)
NOW, let's get to our special Longitude Clues!
The Longitude Problem
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Well, get ready for some help, because here come the clues that we promised for the SPRING EQUINOX. These clues will help you estimate the approximate longitude for 9 of the 10 Mystery Classes. (Remember, they're estimates--they may not provide a location's exact longitude.)
Only on the Equinox (spring or fall) does this clue work. As your graph shows, on the Equinox everyone on earth has about the same amount of daylight. At all other times of year, either the Northern Hemisphere or Southern Hemisphere has more daylight. On the Equinox, neither of the poles of the Earth is tilted toward or away from the sun. Because of this fact, you will be able to estimate approximate LONGITUDE by knowing the time of sunrise at the Mystery Class on the Equinox when you are given that time in Greenwich Mean Time (GMT). Whew, sound confusing? Bear with us, because this is quite amazing!
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.
All Mystery Classes (except one) have revealed what time it will be using Greenwich Mean Time (GMT) when the sun rises at their Mystery site on March 20, 2002 (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 a 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 Equinox Sunrise times table for 9 of the 10 Mystery classes first, and then walk you through two examples. Print it and go. Good Luck!
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 11, 2002
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MYSTERY CLASS |
SUNRISE |
SUNSET |
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#1 |
07:34 |
18:59 |
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#2 |
00:00* |
00:00* |
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#3 |
06:36 |
18:33 |
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#4 |
06:12 |
18:25 |
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#5 |
06:31 |
18:31 |
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#6 |
06:47 |
18:30 |
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#7 |
06:13 |
18:04 |
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#8 |
06:58 |
18:13 |
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#9 |
06:07 |
18:05 |
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#10 |
07:07 |
19:16 |
* Journey North Mystery Class #2 reported 00:00 for their times and left this message for you: "We're looking forward to a sunset at last! "
Note: Military time is usually expressed without any punctuation. We have used a ":" between the hours and minutes for clarity.)
Spring Fever Anyone? Responses to CQ #2
Thanks to all of the classes who answered this Challenge Question. We can tell that you are watching your graphs very carefully! Here are just a few examples:
Mrs. Berlin's Class from Framingham, MA really "lined things up":
"The students in my class have been graphing sunlight hours in our area since the first day of Autumn. They believe that the lines on the graph are all going to come together in two weeks. They won't all be right on the 12 hour line, but they will be close. We aren't certain about the Mystery Class that has been having 24 hours of daylight, but we are guessing that they will follow along with the others, and be moving close to 12 hours of daylight. We believe this will be happening because the first day of Spring is called the Spring Equinox, indicating an equal amount of day and night. This is because of the location of our planet relative to the Sun."
Colili from Robinson School in Puerto Rico answered that "I think that the graph will stay in the 12:30 zone no higher and no lower."
And from Hebron, CT, RHAM Middle School students said "We added the number of minutes our location has been gaining or losing to the photoperiod for the next two weeks and found out that everyone will have almost the same number of minutes for night and day, 12 hours of daylight and 12 hours of night."
Nice going, everyone!
Clues Calendar
After the Longitude Clue, we'll begin sending new interdisciplinary clues every week for the next five weeks, to help you try to narrow your search for each secret Mystery Class location by the April 26 deadline. Here are some important Mystery Class dates for the coming weeks:
- March 15: Longitude
Clues given
- March 22, 29, April 5, 12 & 19: New clues from the Mystery Sites given each week
- April 26: Deadline for Your Answers!
(No late entries accepted)
- May 3: Mystery Sites
Revealed!
- May 10: Meet Your Mystery Friends!
The Next Mystery Class Update Will be Posted on March 22, 2002
Copyright 2002 Journey North. All Rights Reserved.
Please send all questions, comments, and suggestions to our feedback form
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