The Julian calendar, introduced by Julius Caesar in 45 BCE, represented a significant advancement in timekeeping by establishing a 365-day year with an additional day added to every fourth year. This system assumed a solar year of exactly 365.25 days. However, the actual solar year—the time it takes for the Earth to complete one revolution around the Sun—is approximately 365.2422 days. Although this annual difference of 11 minutes and 14 seconds seems minuscule, over the centuries, the Julian calendar's slight overestimation of the year's length caused its dates to drift out of alignment with the astronomical seasons. By the late sixteenth century, the vernal equinox, traditionally observed on March 21, was occurring around March 11 on the calendar. This drift presented a serious problem for the Catholic Church, as the calculation of the date of Easter was strictly tied to the vernal equinox. To rectify this discrepancy, Pope Gregory XIII introduced the Gregorian calendar in 1582. The Gregorian reform advanced the calendar by ten days to restore the equinox to March 21. Furthermore, it refined the existing leap year rule to prevent future drift: under the new system, century years would be counted as leap years only if they were divisible by 400. This modification reduced the average year length to 365.2425 days, bringing it much closer to the true solar year.
Based on the passage, which of the following can be inferred about century years under the Julian calendar?
- AThey were treated as leap years only if they could be evenly divided by 400.
- BThey were recognized by the Catholic Church as the primary reason for the shift in the vernal equinox.
- They were all treated as leap years, regardless of whether they were divisible by 400.Cevap
- DThey were the exclusive cause of the annual discrepancy of 11 minutes and 14 seconds.
- EThey were eliminated entirely from the calendar system by Pope Gregory XIII.