the.com/leapyear
the calendar's quiet apology for the planet that refuses to count in whole numbers
means A year containing an extra day (February 29th) added every four years to keep the calendar aligned with Earth's actual orbit around the sun.
from From Old English 'hlēapgēar' — literally a 'leap' year. The charming logic: in an ordinary year, a fixed date advances one weekday from the year before; but in a year with the extra day, dates after February 'leap' over a weekday, jumping forward two instead of one. The mathematical fix itself is older than the English name — the Romans had wrestled the calendar into shape, and the extra day was bolted onto the end of a short, awkward February that already carried Rome's seasonal scars.
- orbit math
- Earth's year is actually 365.2422 days long
- century rule
- 1900 had no leap day, but 2000 did
- rare birth
- Feb 29 babies are called leaplings, born once per 1,461 days
- caesar's fix
- Julius Caesar invented leap years in 46 BC
- overshoot
- Without correction, July would drift into winter eventually
leap year rule 1900 — 1900 was not a leap year despite divisibility by 4, demonstrating the 400-year exception