Journey North Mystery Class Spring 2004

Mystery Class Update: March 12, 2004

Today's Report Includes:

Is Everything Coming Together? Discussion of CQ #2
Spring Begins March 20--The Longitude Clues are Here!
Note to Teachers with Younger Students
The Longitude Problem
How Time and Longitude are Related
Why Greenwich Mean Time is Important
Let's Get Started
Equinox GMT Sunrise Table, GMT Worksheet & Two Examples
This Week's Sunrise/Sunset Times
Clues Calendar: Plan Ahead

Is Everything Coming Together? Discussion of CQ #2

The Vernal Equinox is March 20

Last week we asked: "What trends have you noticed in your graph? And what do you think it will look like on the Vernal Equinox on March 20, 2004?" We received answers from Arkansas, Connecticut, Florida, Indiana, New York, North Carolina and other places too, so a lot of you must be watching this closely!

Mrs. Bonners's 4th grade class at Highview Elementary School in Nanuet, New York summed it all up predicting that "the photoperiods for our mystery classes will all be at 12 hours... because of the Vernal Equinox. This is when everyone around the globe has daylight for about 12 hours because the earth is not tilted on its axis toward or away from the sun." Hannah, Sydney, Leanne, Alexa, Jeff, Michael.

Students from St. Johns Greek Orthodox 6th and 7th grade groups, Wendy Ikoku's class at Providence Spring Elementary #507, and Mrs. Lodge's class at RHAM Middle School in Hebron CT also followed the lines with their predictions too.

And two classes raised an interesting question for you. Mrs. Work's 5th graders from Evansville, Indiana, and Austin and Ryan from St. Johns Greek Orthodox school are wondering...:

	...will the graph line and photoperiod for MC#6 follow all the others and converge at 12 hours?
This great graph courtesy of Mrs. Work's fifth grade class

What do you think? Keep you eyes on your graphs because the Equinox is coming!

Nice job to everyone!

Spring Begins March 20--The Longitude Clues are Here!
Happy Vernal Equinox! In early celebration, we have gathered a special set of Longitude Clues from the 10 secret Mystery Sites, which will be provided below. The Mystery Classes are eager to be discovered, and this is a big step in that direction. Every year we are told that using these Longitude clues is one of the most exciting and revealing steps in the quest! And more clues will be coming in the following weeks. So have fun and good luck!

IMPORTANT: Be sure that you read and follow ALL the instructions in this report very carefully. We suggest you print this report and work from the printed copies. 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.)

In today's report, we'll also be giving you the latest sunrise and sunset times.

Everything you need to get started is available below.

Note to Teachers with Younger Students
For teachers with 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 activity, 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 (IMPORTANT: Please Read Carefully)

click to enlarge

The changing photoperiods that you've tracked have provided some clues about the LATITUDE of the Mystery Classes. But that photoperiod information doesn't help you much when you try to determine the LONGITUDE of the Mystery Classes.

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) do these clues work. As your graph will show, 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 sunrise 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/Longitude 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, 2004 (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.

Let's Get Started! Now It's Your Turn

Instructions:

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

Mystery Class GMT Worksheet

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 (two freebies!). Be sure to review the two examples below:

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.

Link to This Week's Sunrise/Sunset Data

Note to Teachers: Plan Ahead and Mark Your Clues Calendar
Here's the 2004 Mystery Class Schedule so you know what to expect from Journey North. Please be sure to plan ahead.

February 6- April 16:	Each Friday, Sunrise/Sunset Times are posted for the ten Mystery Sites.
March 12:	The "Longitude Clue" is posted.
March 19, 26, April 2, 9 & 16:	Interdisciplinary clues from the Mystery Sites are posted each week. (Please Note--out of fairness to all participants, we will only post the clues on their scheduled dates.)
April 23: Deadline for Your Answers!	No late entries will be accepted (out of fairness to all participants, no exceptions.)
April 30:	Mystery Sites Revealed!
May 7:	Meet Your Mystery Friends!

The Next Mystery Class Update Will Be Posted on March 19, 2004