Credit & Copyright: Rune Rysstad
Explanation:
Even as leap days go, today is a remarkable one.
In 46 BC,
Julius Caesar, pictured above in a self-decreed minted coin,
created a calendar system that added one
leap day every four years.
Acting on advice by Alexandrian astronomer
Sosigenes, Caesar did this to make up for the fact that the
Earth's year is slightly more than 365 days.
In modern terms, the time it takes for the Earth to circle
the Sun is slightly more than the time it takes for the
Earth to rotate 365 times (with respect to the Sun -- actually
we now know this takes about 365.24219 rotations).
So, if calendar years contained 365 days they would drift
from the actual year by about 1 day every 4 years.
Eventually July (named posthumously for
Julius Caesar himself)
would occur during the northern hemisphere winter!
By adopting a leap year with an extra day every four years, the
calendar year would drift much less.
This Julian Calendar system was used until the year 1582 when
Pope Gregory XIII added that leap days
should not occur in years ending in "00" except
if divisible by 400, providing further fine-tuning.
This Gregorian Calendar system is the one in common use today.
Therefore, even though this year 2000 ends in "00", it remains a
leap year, and today is the added leap day.
That makes today the first leap day
for a centurial year since year 1600 and the second
such leap day of the Gregorian Calendar.
1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 |
Январь Февраль Март Апрель Май Июнь Июль Август Сентябрь Октябрь Ноябрь Декабрь |
NASA Web Site Statements, Warnings, and Disclaimers
NASA Official: Jay Norris. Specific rights apply.
A service of: LHEA at NASA / GSFC
& Michigan Tech. U.
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Публикации с ключевыми словами:
Julius Caesar - Leap Days
Публикации со словами: Julius Caesar - Leap Days | |
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