The Easter Paradox
If the first full moon of spring according to astronomical data fails to match with the Easter Sunday according to the calculated prediction, the “Easter paradox” occurs. Below is a table of the years between 1583 and 2599, where such a paradox occurs. An extreme example is the spring of 1666. The beginning of spring that year began on Saturday, the 20th of March at 8:44 with the astronomical full moon occuring at 6:01 pm. If this prediction were used, Sunday, the 21st of March, would have been the day to celebrate Easter Sunday. However, the ecclesiastical full moon (and its corresponding start of spring) was predicted as the 18th of April, and because of this, Easter Sunday was not celebrated until the following Sunday, 25 April. This created a whopping 35-day difference!
If you take note of the years on the table where Easter was celebrated 28 days later, these years typically have an epact of 24. As can be seen in the table NOVILUNIORUM for epact 24, the predicted new moon falls on 7 March, putting the full moon at 20 March. This places it just before the beginning of the church’s official date for the start of spring: 21 March. In effect, what we have is one calculation saying the full moon is on 20 March (ecclesiastical) and the other calculation saying it’s on the 21st (astronomical). And because it’s a day behind the start of spring, the ecclesiastically-based calculation used for determining Easter needs to wait for another new moon, with the next one coming up on 5 April. From this start point, the first full moon occurs much later, pushing the date of Easter to the 18th of April. It’s because of this incongruity that there’s a recurring 28 day error in the calculation of Easter Sunday. This difference is often repeated after 19 years, following the nineteen-year cycle of the Golden Number, in which the same epacts repeat throughout a given century.
| Year | Easter is celebrated on … | Beginning of spring | astronomical full moon | astronomical Easter Sunday | Ecclesiastical full moon | actual Easter Sunday |
|---|---|---|---|---|---|---|
| 1590 | 28 days later | Mar 20 22:42 | Mar 21 05:04 | Mar 25 | Apr 18 | Apr 22 |
| 1598 | 7 days prior | Mar 20 21:09 | Mar 22 21:40 | Mar 29 | Mar 21 | Mar 22 |
| 1622 | 7 days prior | Mar 20 16:40 | Mar 27 02:59 | Apr 3 | Mar 26 | Mar 27 |
| 1629 | 7 days later | Mar 20 09:29 | Apr 7 20:34 | Apr 8 | Apr 8 | Apr 15 |
| 1666 | 35 days later | Mar 20 08:44 | Mar 20 18:01 | Mar 21 | Apr 18 | Apr 25 |
| 1680 | 7 days later | Mar 19 18:10 | Apr 13 23:35 | Apr 14 | Apr 14 | Apr 21 |
| 1685 | 28 days later | Mar 19 23:15 | Mar 20 17:46 | Mar 25 | Apr 18 | Apr 22 |
| 1693 | 7 days prior | Mar 19 21:37 | Mar 22 02:00 | Mar 29 | Mar 21 | Mar 22 |
| 1700 | 7 days later | Mar 20 14:26 | Apr 3 18:15 | Apr 4 | Apr 4 | Apr 11 |
| 1724 | 7 days later | Mar 20 10:08 | Apr 8 15:31 | Apr 9 | Apr 9 | Apr 16 |
| 1744 | 7 days later | Mar 20 06:21 | Mar 28 08:54 | Mar 29 | Mar 29 | Apr 5 |
| 1778 | 7 days later | Mar 20 12:21 | Apr 11 20:20 | Apr 12 | Apr 12 | Apr 19 |
| 1798 | 7 days later | Mar 20 08:38 | Mar 31 22:43 | Apr 1 | Apr 1 | Apr 8 |
| 1802 | 7 days prior | Mar 21 07:48 | Apr 18 02:36 | Apr 25 | Apr 17 | Apr 18 |
| 1818 | 7 days prior | Mar 21 04:49 | Mar 22 14:09 | Mar 29 | Mar 21 | Mar 22 |
| 1825 | 7 days prior | Mar 20 21:25 | Apr 3 06:27 | Apr 10 | Apr 2 | Apr 3 |
| 1845 | 7 days prior | Mar 20 17:43 | Mar 23 20:19 | Mar 30 | Mar 22 | Mar 23 |
| 1876 | 7 days later | Mar 20 06:10 | Apr 8 19:39 | Apr 9 | Apr 9 | Apr 16 |
| 1900 | 7 days prior | Mar 21 01:39 | Apr 15 01:02 | Apr 22 | Apr 14 | Apr 15 |
| 1903 | 7 days prior | Mar 21 19:15 | Apr 12 00:18 | Apr 19 | Apr 11 | Apr 12 |
| 1923 | 7 days prior | Mar 21 15:29 | Apr 1 13:10 | Apr 8 | Mar 31 | Apr 1 |
| 1924 | 28 days later | Mar 20 21:20 | Mar 21 04:30 | Mar 23 | Apr 18 | Apr 20 |
| 1927 | 7 days prior | Mar 21 14:59 | Apr 17 03:35 | Apr 24 | Apr 16 | Apr 17 |
| 1943 | 28 days later | Mar 21 12:03 | Mar 21 22:08 | Mar 28 | Apr 18 | Apr 25 |
| 1954 | 7 days prior | Mar 21 03:53 | Apr 18 05:48 | Apr 25 | Apr 17 | Apr 18 |
| 1962 | 28 days later | Mar 21 02:30 | Mar 21 07:54 | Mar 25 | Apr 18 | Apr 22 |
| 1967 | 7 days prior | Mar 21 07:37 | Mar 26 03:20 | Apr 2 | Mar 25 | Mar 26 |
| 1974 | 7 days later | Mar 21 00:07 | Apr 6 20:59 | Apr 7 | Apr 7 | Apr 14 |
| 2019 | 28 days later | Mar 20 21:58 | Mar 21 01:42 | Mar 24 | Apr 18 | Apr 21 |
| 2038 | 28 days later | Mar 20 12:40 | Mar 21 02:08 | Mar 28 | Apr 18 | Apr 25 |
| 2045 | 7 days later | Mar 20 05:07 | Apr 1 18:42 | Apr 2 | Apr 2 | Apr 9 |
| 2049 | 7 days prior | Mar 20 04:27 | Apr 18 01:02 | Apr 25 | Apr 17 | Apr 18 |
| 2057 | 28 days later | Mar 20 03:07 | Mar 21 00:43 | Mar 25 | Apr 18 | Apr 22 |
| 2069 | 7 days later | Mar 20 00:44 | Apr 6 16:11 | Apr 7 | Apr 7 | Apr 14 |
| 2076 | 28 days later | Mar 19 17:37 | Mar 20 16:35 | Mar 22 | Apr 18 | Apr 19 |
| 2089 | 7 days later | Mar 19 21:05 | Mar 26 09:17 | Mar 27 | Mar 27 | Apr 3 |
| 2095 | 28 days later | Mar 20 08:14 | Mar 21 01:07 | Mar 27 | Apr 18 | Apr 24 |
| 2096 | 7 days later | Mar 19 14:02 | Apr 7 18:15 | Apr 8 | Apr 8 | Apr 15 |
| 2106 | 7 days prior | Mar 21 00:03 | Apr 18 08:17 | Apr 25 | Apr 17 | Apr 18 |
| 2114 | 28 days later | Mar 20 22:38 | Mar 21 09:13 | Mar 25 | Apr 18 | Apr 22 |
| 2119 | 7 days prior | Mar 21 03:38 | Mar 26 23:52 | Apr 2 | Mar 25 | Mar 26 |
| 2133 | 28 days later | Mar 20 13:14 | Mar 21 00:13 | Mar 22 | Apr 18 | Apr 19 |
| 2147 | 7 days prior | Mar 20 22:31 | Apr 16 03:05 | Apr 23 | Apr 14 | Apr 16 |
| 2150 | 7 days prior | Mar 20 16:01 | Apr 12 00:10 | Apr 19 | Apr 11 | Apr 12 |
| 2152 | 28 days later | Mar 20 03:37 | Mar 20 22:18 | Mar 26 | Apr 18 | Apr 23 |
| 2170 | 7 days prior | Mar 20 12:27 | Apr 1 06:32 | Apr 8 | Mar 31 | Apr 1 |
| 2171 | 28 days later | Mar 20 18:08 | Mar 21 22:51 | Mar 24 | Apr 18 | Apr 21 |
| 2174 | 7 days prior | Mar 20 11:26 | Apr 17 06:55 | Apr 24 | Apr 16 | Apr 17 |
| 2190 | 28 days later | Mar 20 08:43 | Mar 21 20:26 | Mar 28 | Apr 18 | Apr 25 |
| 2221 | 7 days later | Mar 20 21:00 | Apr 7 20:02 | Apr 8 | Apr 8 | Apr 15 |
| 2245 | 7 days prior | Mar 20 16:41 | Apr 13 01:27 | Apr 20 | Apr 12 | Apr 13 |
| 2277 | 28 days later | Mar 20 10:49 | Mar 20 12:37 | Mar 25 | Apr 18 | Apr 22 |
| 2292 | 7 days later | Mar 20 01:49 | Apr 2 15:37 | Apr 3 | Apr 3 | Apr 10 |
| 2296 | 28 days later | Mar 20 01:21 | Mar 20 10:51 | Mar 22 | Apr 18 | Apr 19 |
| 2299 | 7 days prior | Mar 20 18:49 | Apr 16 06:10 | Apr 23 | Apr 15 | Apr 16 |
| 2316 | 7 days later | Mar 20 21:38 | Apr 8 20:24 | Apr 9 | Apr 9 | Apr 16 |
| 2336 | 7 days later | Mar 20 18:00 | Mar 28 07:16 | Mar 29 | Mar 29 | Apr 5 |
| 2339 | 7 days prior | Mar 21 11:17 | Mar 26 11:02 | Apr 2 | Mar 25 | Mar 26 |
| 2353 | 28 dní dříve | Mar 20 20:46 | Apr 19 10:44 | Apr 19 | Mar 21 | Mar 22 |
| 2372 | 28 dní dříve | Mar 20 11:26 | Apr 18 22:33 | Apr 23 | Mar 21 | Mar 26 |
| 2390 | 7 days later | Mar 20 20:00 | Mar 31 18:38 | Apr 1 | Apr 1 | Apr 8 |
| 2394 | 7 days prior | Mar 20 19:24 | Apr 17 01:11 | Apr 24 | Apr 16 | Apr 17 |
| 2410 | 28 days later | Mar 20 16:21 | Mar 21 09:35 | Mar 28 | Apr 18 | Apr 25 |
| 2417 | 7 days prior | Mar 20 08:59 | Apr 2 01:19 | Apr 9 | Apr 1 | Apr 2 |
| 2421 | 7 days prior | Mar 20 08:15 | Apr 18 06:34 | Apr 25 | Apr 17 | Apr 18 |
| 2429 | 28 days later | Mar 20 07:02 | Mar 21 06:31 | Mar 25 | Apr 18 | Apr 22 |
| 2437 | 7 days prior | Mar 20 05:18 | Mar 22 16:56 | Mar 29 | Mar 21 | Mar 22 |
| 2448 | 28 days later | Mar 19 21:27 | Mar 20 19:50 | Mar 22 | Apr 18 | Apr 19 |
| 2451 | 7 days prior | Mar 20 14:59 | Apr 16 08:31 | Apr 23 | Apr 15 | Apr 16 |
| 2467 | 28 days later | Mar 20 12:01 | Mar 21 03:15 | Mar 27 | Apr 18 | Apr 24 |
| 2468 | 7 days later | Mar 19 17:53 | Apr 7 20:56 | Apr 8 | Apr 8 | Apr 15 |
| 2471 | 7 days prior | Mar 20 11:07 | Apr 5 15:59 | Apr 12 | Apr 4 | Apr 5 |
| 2486 | 28 days later | Mar 20 02:33 | Mar 20 12:56 | Mar 24 | Apr 18 | Apr 21 |
| 2488 | 7 days later | Mar 19 14:11 | Mar 27 22:39 | Mar 28 | Mar 28 | Apr 4 |
| 2491 | 7 days prior | Mar 20 07:26 | Mar 26 05:38 | Apr 1 | Mar 24 | Mar 25 |
| 2492 | 7 days prior | Mar 19 13:17 | Apr 13 03:06 | Apr 20 | Apr 12 | Apr 13 |
| 2495 | 7 days prior | Mar 20 06:38 | Apr 10 00:10 | Apr 17 | Apr 9 | Apr 10 |
| 2515 | 7 days prior | Mar 21 02:59 | Mar 31 06:13 | Apr 7 | Mar 30 | Mar 31 |
| 2519 | 7 days prior | Mar 21 02:23 | Apr 16 07:02 | Apr 23 | Apr 15 | Apr 16 |
| 2546 | 7 days prior | Mar 20 15:30 | Apr 17 10:03 | Apr 24 | Apr 16 | Apr 17 |
| 2586 | 7 days prior | Mar 20 07:59 | Mar 26 04:57 | Apr 2 | Mar 25 | Mar 26 |
| 2590 | 7 days prior | Mar 20 07:15 | Apr 11 01:34 | Apr 18 | Apr 10 | Apr 11 |