Back Start Over

A Clue About Longitude Clues Why They Only Work on the Equinox The Mystery Class longitude clues will tell you what time it was in Greenwich, England (0 degrees longitude) when the sun rose at each Mystery Class site on the equinox. From this, you'll be able to estimate each site's longitude. What questions do you still have? You'll learn more when you get your longitude clues! In the meantime, try this: Eating on the Equinox. We can estimate Mystery Class longitudes by calculating how much time passed between GMT sunrise at Greenwich (shown here) and sunrise at each mystery site!