The illusion of a stationary Earth
The sun takes center stage
The math of a year
Solving the calendar puzzle
YOUR GOAL
Master of How we found our place in space
futura Earth Orbits the Sun
We once thought all revolved around our sphere, But Earth orbits the Sun, to define our whole year!
futura The ancient Maya developed exceptionally precise calendars based on highly sophisticated astronomical observations.
futura Pope Gregory XIII corrected the Julian calendar's drift by skipping ten days and adjusting leap year rules.
futura Solve the calendar puzzle in this interactive game. Discover how we learned the Earth orbits the Sun and how that shaped our modern calendar.
Lost October days: In October 1582, people in Catholic Europe went to sleep on October 4 and woke up on October 15.
A calendar year containing an extra day to keep it synchronized with the astronomical year. In 45 BCE, Julius Caesar introduced this extra day to synchronize Roman calendars with Earth's orbit.
In which year did Pope Gregory XIII introduce the Gregorian calendar to correct the errors of the Julian calendar?
What is occasionally added to modern atomic clocks to keep Coordinated Universal Time in sync with Earth's slowing rotation?
Why does the Islamic calendar shift about 11 days earlier relative to the Gregorian calendar each year?
What type of calendar is the traditional Chinese calendar, which combines solar cycles and lunar phases?
Who introduced the Julian calendar in 46 BCE, establishing a leap year every four years?