Clues for Spring 2020*

*Please note: Our spring 2020 Mystery Class challenge is a replay of a previous year's challenge. On this page, you have open access to all clues (Weeks 1-11). We will reveal the locations of the 10 Mystery sites on April 13, 2020.


Time Continent, Country, City

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

From the Mystery Sites

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


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?


Use Time Clues to estimate longitude:

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

Continent/Region Clues

Country Clues

State/Province Clues

City/Town Clues


Coming April 13, 2020

Locations of the 10 Mystery Sites will be revealed.