Mystery Class Sunlight Challenge: Week #7
March 9, 2018 by Julie Brophy

The Time Clues are here to help you estimate the longitude of Mystery sites. But first, get some latitude and longitude flow with this music video from
Ms. Ciolkosz's Mystery Class Club in Pennsylvania (40.7 N, 78.0 W).

Ms. Ciolkosz's Mystery Class Club in Pennsylvania Furnace, PA, choreographed and performed this video. The club meets about twice a month after school, and includes students from home, private, and public schools. Like you, they're searching for the ten secret sites too.


Photoperiod Clues from the Mystery Sites

Mystery Class Photoperiod Map

Compare Your Photoperiod

Report Photoperiod

Mystery Class Photoperiod Map


Time Clues: Estimating Longitude
Make one copy for locating each Mystery Class site.

Sunrise on the Equinox Table Longitude Clues Worksheet Map
Time Clues
Sunrise on the Equinox
Step-by-step guide
Plot east/west location

Sunrise on the Equinox

View animation as you work. You can estimate the longitude of each mystery site with the Time Clues and these key facts:

  • The Earth turns to the east as it rotates.
  • It spins 1 degree longitude every 4 minutes.
  • The time between sunrise at the Prime Meridian and sunrise at a mystery site on the equinox reveals approximate longitude.
Sample Worksheets for Practice
Longitude Clues Worksheet Longitude Clues Worksheet Longitude Clues Worksheet
Sample A
West of Greenwich
Sample B
East of Greenwich
Sample C
Farther east of Greenwich
Next Update March 16, 2018