Hurdling Past the Leap Years

People love having tools for observing the passage of time, like calendars, which allow us to mark off the days, weeks, months and years. The Gregorian calendar was set up to measure the amount of time it takes the Earth to move around the Sun. It takes the Earth 364 days plus a fraction of a day to do that, which means, adjustments had to be made to keep the calendar on track, through the addition of Leap Days in those years we call Leap Years.

What Is Leap Year?

It takes earth 365 days plus 5 hours, 48 minutes and 57 seconds to make its way around the Sun, which makes it difficult to plan into a calendar. So, when creating the Gregorian calendar, each year was measured as exactly 365 days. The question, then, was what to do with that leftover time, because after a number of years, the calendar would begin drifting off – by about 1 day every 4 years -until the seasons no longer aligned. So the calendar was tweaked, to add that time back in to the calendar and keep it on course. The Leap Year adds one day to the month of February every 4^th year, giving that year 366 days instead of 365 days.

Leap Years and Leap Centuries

The addition of one day every 4 years, wasn’t quite enough, though. The calendar was still losing about 1 day every 100 years. As a result, every 400 years, the calendar year would end up 1 day short. So, the Leap Century system was added, to continue keeping the calendar in line.

Century years fall into the fourth year cycle. Under normal years, this would make them a leap year. The Leap Century systems allows for 3 out of every 4 of those century years to be regular years (365 days), with the fourth century year marked as a Leap Century that adds the Leap Day back into the month of February. As an example, the century years of 1700, 1800 and 1900 were regular years, having 365 days, while the century year 2000

The exception to the 4 year rule occurs with the centuries. Every fourth century year is a leap century, but the other three century years don't have a leap day added. So 2000 was a leap century but 2100, 2200 and 2300 will not be leap centuries.

List of Leap Years from 1800 Through 2400

The following list shows all the leap years, from the 19^th century to the 25^th century. Notice that the century years that are not leap years have been omitted from the list.

1804, 1904, 2004, 2104, 2204, 2304

1808, 1908, 2008, 2108, 2208, 2308

1812, 1912, 2012, 2112, 2212, 2312

1816, 1916, 2016, 2116, 2216, 2316

1820, 1920, 2020, 2120,2220, 2320

1824, 1924, 2024, 2124, 2224, 2324

1828, 1928, 2028, 2128, 2228, 2328

1832, 1932, 2032, 2132, 2232, 2332

1836, 1936, 2036, 2136, 2236, 2336

1840, 1940, 2040, 2140, 2240, 2340

1844, 1944, 2044, 2144, 2244, 2344

1848, 1948, 2048, 2148, 2248, 2348

1852, 1952, 2052, 2152, 2252, 2352

1856, 1956, 2056, 2156, 2256, 2356

1860, 1960, 2060, 2160, 2260, 2360

1864, 1964, 2064, 2164, 2264, 2364

1868, 1868, 2068, 2169, 2268, 2368

1872, 1972, 2072, 2172, 2272, 2372

1876, 1976, 2076, 2176, 2276, 2376

1880, 1980, 2080, 2180, 2280, 2380

1884, 1984, 2084, 2184, 2284, 2384

1888, 1988, 2088, 2188, 2288, 2388

1892, 1992, 2092, 2192, 2292, 2392

1896, 1996, 2096, 2196, 2296, 2396

2000, 2400

References

Astronomy and the Solar System. Calendars. Downloaded 1/4/2012. http://csep10.phys.utk.edu/astr161/lect/time/calendars.html

Kalendar-365. List of Leap Years.

http://kalender-365.de/leap-years.php

Time and Date. Leap Year: 2012 Is a Leap Year.

http://www.timeanddate.com/date/leapyear.html