The Mayan calendar keepers painstakingly charted the cycles of the moon, the sun, and Venus. Their uncanny accuracy was not duplicated until modern times. As Lawrence Joseph notes, “Without telescopes or any other apparatus, Mayan astronomers calculated the length of the lunar month to be 29.53020 days, within 34 seconds of what we now know to its actual length of 29.53059 days. Overall, the 2000-year-old Mayan calendar is believed by many to be more accurate than the 500-year-old Gregorian calendar