Use photoperiod to estimate latitude. Calculate photoperiod using sunrise/sunset data.

Use the weekly sunrise/sunset data from the 10 Mystery sites to calculate the photoperiod for each site. Record and graph the photoperiods.

• Week 1: January 27
• Week 2: February 3
• Week 3: February 10
• Week 4: February 17
• Week 5: February 24
• Week 6: March 2
• Week 7: March 9
• Week 8: March 16
• Week 9: March 23
• Week 10: March 30
• Week 11: April 6

Your Local Data

How does your photoperiod compare to the Mystery Sites?

Google your own sunrise/sunset for the dates above. Calculate, record and graph your photoperiod.

What does photoperiod reveal about the geographic location of a place?

Narrow the search from continent to country to city. Clues will be posted weekly on these dates.

Continent/Region Clues

• Week 8: March 16

Country Clues

• Week 9: March 23

State/Province Clues

• Week 10: March 30

City/Town Clues

• Week 11: April 6

Locations of the 10 Mystery Sites will be revealed.