Tracking Changes in Photoperiod Around the Globe

Mystery Class Update: March 21, 1997

"During the great ages of exploration, 'the longitude problem' was the gravest of scientific challenges. Lacking the ability to determine their longitude, sailors were literally lost at seas as soon as they lost sight of land. Ships ran aground on rocky shores, those traveling well-known routes were easy prey to pirates.

"In 1714, England's Parliament offered a huge reward to anyone whose method of measuring longitude could be proven successful. (The prize was worth several million dollars in today's currency.) The scientific establishment--from Galileo to Sir Issac Newton--had mapped the heavens, in its certainty of a celestial answer. In stark contrast, one man dared to imagine a mechanical solution--a clock that would keep precise time at seas, something no clock had been able to do on land. And the race was on..." Longitude: The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of His Time. By Dava Sobel, Penguin Books, 1995.

As you may have noticed, you have a longitude problem of your own! The sunrise and sunset times so far have given you certain information about the location of the Mystery Classes. Can you answer Challenge Question #3?

Challenge Question #3:
"What do you know about the longitude of each location? What do you know about their latitude?"

To respond to this Challenge Question, please follow the instructions at the end of this report. In your answer, give examples of what you know and don't know about the locations of specific sites. Compare the location of one Mystery Class to the other.

Celebrating Spring!
In celebration of yesterday's Vernal Equinox, we are gathering a special set of clues from the Mystery Classes which we will provide in next week's Update.

In the meantime, this week's sunrise and sunset data has been carefully compiled and sent to us by Mrs. Berger's class, and we have put the data for you below. Be sure to look closely at the times for Mystery Class numbers 3 and 6 and see if you can answer Challenge Question #4:

Challenge Question #4:
"Do you notice anything unusual in the times listed for Mystery Classes numbers 3 and 6? What do you notice, and can you explain why this happened?

To respond to this Challenge Question, please follow the instructions at the end of this report.

Here's the data for this week:

Journey North Mystery Class
Sunrise/Sunset Data

Data For: Monday, February 17, 1997

Last Week's Challenge Question
With the addition of this week's data, does your Mystery Class graph look the way you expected? Many classes answered our challenge question about this from last week, when we asked, "What do you think your graph will look like on March 20, 1997? Why do you think so?" All the classes told us that March 20 is the first day of Spring or the "Vernal Equinox", where daylength at all places on the planet is 12 hours! Two classrooms in Maine really "sprung" into action and sent in their responses to last week's springtime Challenge Question and here's what they had to say:

"Happy Spring Equinox Journey North!!!!
We have had quite a discussion up here in still icy, snowy Maine about the reasons that every one on planet earth will have 12 hours of daylight and 12 hours of dark on March 20th. We all agree that it has to do with the tilt of the earth's axis and the place that the earth is in its orbit around the sun. What has been hard for us to believe and remember is that it is not the tilt that changes - when we look at a model of the earth and sun we see the tilt is the same - what is different is the earth's place in its orbit around the sun. I'd really be interested in how others are learning about this concept. We also have a huge graph with all the mystery classes and it is quite obvious that all lines will meet at 12 hours on the 20th. Sarah made a very interesting observation. She said that the position of each of the classes on the graph was like looking at its location on the globe."
=46rom Grade 5 at Pemetic School in Southwest Harbor, Maine
=46ran Howley (grade5fh@pemetic.u98.k12.me.us)

"On March 20th on both sides of the equator there will be twelve hours of day and twelve hours of night. All the mystery classes will meet at the 12 hour point on the graph because the sun is directly over the equator. This is the spring equinox. Happy Spring!!!"
Dan in Mr. Koenka's fifth grade class at the Penobscot Elementary School in Penobscot, Maine
David Koenka (koenka@penobscot.u93.k12.me.us)

Several other classes put a lot of thought into answering this question and here are their answers:

From: NEW JERSEY
We think that the time for the 20th will be 12 hours.
from Samantha, Danielle, Monica, Alison, Danny, Brian, Ryan,and Mike
Tracey Schaum (oradell@intac.com)

From: ILLINOIS
On Thursday March 20, 1997 my mystery class graph will have a big spot on it, right in the middle. I came to this conclusion because on my graph all of the mystery classes are coming to a point where they will soon intersect. Also, on Thursday the seasons change which cause virtually the same photoperiod worldwide.
Travis Matthews
On March 20, 1997, my graph will have all of the mystery class data intersecting, or about to intersect. I guessed this because right now I have one line already intersecting about three or four other classes. Mystery Class #6 may not intersect because of the odd angle that it is at. Erica Moeller
Mr. VanAntwerp"s 6th grade class
James HArt Junior High
Homewood, IL 60430
Gary G Vanantwerp (gvanant@uxa.ecn.bgu.edu)

From: MASSACHUSETTS
We think that on March 20th every place in the world will have twelve hours of sunlight and twelve hours of darkness! This happens because on the 20th the sun will be directly over the equator since the earth is facing sideways toward the sun.
Sharon Daylight Patriots
Heights Elementary School
Sharon, MA
Maddy Shapiro (Maddy_Shapiro@sharon.k12.ma.us)

From: NEW YORK
The Mystreies Schools photoperiod lines are coming to almost the same point in hours of daylight. our prediction for what the graph will look like on March 20 is that the Hours of daylight will be the same because of the way the Earth is on its axis and the way it's turning.
Sheridee Rocco
Ms. Maloy's Class
Clara H. Carlson School
Elmont N.Y.
Mrs.Richards, Computer teacher
PHYLLIS RICHARDS (K12ELPZR@vaxc.hofstra.edu)

From: MINNESOTA
On the 20th of March,all the photo periods will be at 12:00 because the 20th is the Spring Equinox when the photo period of all the mystery cities will be the same.
Dylan Bauer, Katherine Curren Challenge Class, Grade 3
Sue DeWit (sue_dewit@hopkins.k12.mn.us)

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How to Respond to Today's Challenge Questions:
Please DO NOT answer both questions in one message!

How to Respond to Journey North Mystery Class Challenge Question #3

1. Address an E-mail message to: jn-challenge-mclass@learner.org
2. In the Subject Line of your message write: Challenge Question #3
3. In the body of the message, give your answer to this question:

Challenge Question #3:
"From the data so far, what do you know about the longitude of each location? What do you know about their latitude?"

How to Respond to Journey North Mystery Class Challenge Question #4

1. Address an E-mail message to: jn-challenge-mclass@learner.org
2. In the Subject Line of your message write: Challenge Question #4
3. In the body of the message, give your answer to this question:

Challenge Question #4:
"Do you notice anything unusual in the times listed for Mystery Classes numbers 3 and 6? What do you notice, and can you explain why this happened?

Don't Forget!
Please tell us who you are! Include the name of your school, and your state or province.

The Next Mystery Class Update Will Be Posted on: March 28, 1997