📜 History of the Gregorian Calendar
Der gregorianische Kalender ersetzte den julianischer Kalender, which had been in use since 46 BCE under Julius Caesar. The Julian calendar assumed a year of exactly 365.25 days, but the actual solar year is approximately 365.2422 days — a difference of about 11 minutes per year. By the 16th century, this had caused the calendar to drift by about 10 days, moving the vernal equinox (important for calculating Easter) away from März 21.
In Oktober 1582, Papst Gregor XIII. introduced the reformed calendar, skipping 10 Tage (Oktober 4 was followed by Oktober 15) and adjusting the leap year rules to prevent future drift. The reform was gradually adopted across the world over the following centuries.
📅 Structure: Months of the Jahr
The Gregorian calendar has 12 months with a total of 365 Tage (366 in a leap year). The names of the months come from Latin and Roman traditions.
| # | Monat | Tage | Lateinischer Ursprung | Jahreszeit (N. Hemisphere) |
|---|---|---|---|---|
| 1 | Januar | 31 | Janus (Gott der Anfänge) | Winter |
| 2 | Februar | 28 (29 im Schaltjahr) | Februa (Reinigungsfest) | Winter |
| 3 | März | 31 | Mars (Kriegsgott) | Frühling |
| 4 | April | 30 | Aperire (öffnen) | Frühling |
| 5 | Mai | 31 | Maia (Göttin des Wachstums) | Frühling |
| 6 | Juni | 30 | Juno (Königin der Götter) | Sommer |
| 7 | Juli | 31 | Julius Caesar | Sommer |
| 8 | August | 31 | Augustus Caesar | Sommer |
| 9 | September | 30 | Septem (seven — 7th in old calendar) | Herbst |
| 10 | Oktober | 31 | Octo (eight) | Herbst |
| 11 | November | 30 | Novem (nine) | Herbst |
| 12 | Dezember | 31 | Decem (ten) | Winter |
🗓 Leap Jahr Checker
A year is a leap year if it is divisible by 4, except for century years (divisible by 100), which must also be divisible by 400.
⚖️ Gregorian vs. Other Calendars
| Calendar | Typ | Jahreslänge | Ära-Beginn | Aktuelles Jahr (2026 n. Chr.) |
|---|---|---|---|---|
| Gregorianisch | Solar | 365.2425 Tage | 1 n. Chr. (Geburt Christi) | 2026 |
| Julianisch | Solar | 365.25 Tage | 45 v. Chr. | 2026 (13 Tage zurück) |
| Hidschri (islamisch) | Lunar | 354.37 Tage | 622 n. Chr. (Hidschra) | 1447–1448 AH |
| Hebräisch | Lunisolar | 353–385 Tage | 3761 v. Chr. (Schöpfung) | 5786–5787 AM |
| Persisch (Solar-Hidschri) | Solar | 365.2422 Tage | 622 n. Chr. (Hidschra) | 1404–1405 SH |
| Chinesisch | Lunisolar | 354–384 Tage | 2697 v. Chr. (Gelber Kaiser) | Jahr 4724 |