There are three well-known records from what is believed to have been an extensive Mayan library, dating back perhaps one thousand years to the height of the Mayan civilization. One of these books is called the Dresden Codex because it was discovered in the late 1800s in the archives of a library in Dresden, Germany. It includes observations of the motions of the Moon and Venus, and predictions of the times at which lunar eclipses would occur.

Perhaps the most remarkable section of the Dresden Codex is a complete record of the orbit of Venus around the Sun. Mayan astronomers had correctly calculated that it takes Venus 584 days to complete its orbit. They arrived at this figure by counting the number of days that Venus first appeared in the sky in the morning, the days when it first appeared in the evening, and the days that it was blocked from view because it was on the opposite side of the Sun. The Mayans then marked the beginning and ending of the cycle with the heliacal rising, the day on which Venus rises at the same time as the Sun.