📜 History of the Gregorian Calendar
Kalender Gregorian menggantikan kalender Julian, 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 Maret 21.
In Oktober 1582, Paus Gregorius XIII introduced the reformed calendar, skipping 10 hari (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 Tahun
The Gregorian calendar has 12 months with a total of 365 hari (366 in a leap year). The names of the months come from Latin and Roman traditions.
| # | Bulan | Hari | Asal Latin | Musim (N. Hemisphere) |
|---|---|---|---|---|
| 1 | Januari | 31 | Janus (dewa permulaan) | Musim Dingin |
| 2 | Februari | 28 (29 pada tahun kabisat) | Februa (festival penyucian) | Musim Dingin |
| 3 | Maret | 31 | Mars (dewa perang) | Musim Semi |
| 4 | April | 30 | Aperire (membuka) | Musim Semi |
| 5 | Mei | 31 | Maia (dewi pertumbuhan) | Musim Semi |
| 6 | Juni | 30 | Juno (ratu para dewa) | Musim Panas |
| 7 | Juli | 31 | Julius Caesar | Musim Panas |
| 8 | Agustus | 31 | Augustus Caesar | Musim Panas |
| 9 | September | 30 | Septem (seven — 7th in old calendar) | Musim Gugur |
| 10 | Oktober | 31 | Octo (eight) | Musim Gugur |
| 11 | November | 30 | Novem (nine) | Musim Gugur |
| 12 | Desember | 31 | Decem (ten) | Musim Dingin |
🗓 Leap Tahun 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 | Jenis | Panjang Tahun | Awal Era | Tahun Ini (2026 M) |
|---|---|---|---|---|
| Gregorian | Matahari | 365.2425 hari | 1 M (kelahiran Kristus) | 2026 |
| Julian | Matahari | 365.25 hari | 45 SM | 2026 (tertinggal 13 hari) |
| Hijriah (Islam) | Bulan | 354.37 hari | 622 M (Hijrah) | 1447–1448 AH |
| Ibrani | Lunisolar | 353–385 hari | 3761 SM (penciptaan) | 5786–5787 AM |
| Persia (Hijriah Matahari) | Matahari | 365.2422 hari | 622 M (Hijrah) | 1404–1405 SH |
| Tiongkok | Lunisolar | 354–384 hari | 2697 SM (Kaisar Kuning) | Tahun 4724 |