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Astronomy Picture of the Day - Julius Caesar and Leap Days
NASA ^ | 29 Feb, 2024 | Image Credit & License: Classical Numismatic Group, Inc., Wikimedia

Posted on 02/29/2024 12:43:11 PM PST by MtnClimber

Explanation: In 46 BC Julius Caesar reformed the calendar system. Based on advice by astronomer Sosigenes of Alexandria, the Julian calendar included one leap day every four years to account for the fact that an Earth year is slightly more than 365 days long. In modern terms, the time it takes for the planet to orbit the Sun once is 365.24219 mean solar days. So if calendar years contained exactly 365 days they would drift from the Earth's year by about 1 day every 4 years and eventually July (named for Julius Caesar himself) would occur during the northern hemisphere winter. By adopting a leap year with an extra day every four years, the Julian calendar year would drift much less. In 1582 Pope Gregory XIII provided the further fine-tuning that leap days should not occur in years ending in 00, unless divisible by 400. This Gregorian Calendar system is the one in wide use today. Of course, tidal friction in the Earth-Moon system slows Earth's rotation and gradually lengthens the day by about 1.4 milliseconds per century. That means that leap days like today will not be necessary, about 4 million years from now. This Roman silver coin, a denarius, depicts Julius Caesar (left) and Venus, Roman goddess of love.


TOPICS: Astronomy; Astronomy Picture of the Day; Science
KEYWORDS: apod; astronomy; godsgravesglyphs; leapday; leapyear; nasa; romanempire; science
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For more detail go to the link and click on the image for a high definition image. You can then move the magnifying glass cursor then click to zoom in and click again to zoom out. When zoomed in you can scan by moving the side bars on the bottom and right side of the image.

1 posted on 02/29/2024 12:43:11 PM PST by MtnClimber
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To: MtnClimber

2 posted on 02/29/2024 12:43:25 PM PST by MtnClimber (For photos of scenery and wildlife, click on my screen name for my FR home page. More photos added.)
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To: 21stCenturion; 21twelve; 4everontheRight; abb; AFB-XYZ; AFPhys; Agatsu77; America_Right; ...
Pinging the APOD list.

🪐 🌟 🌌 🍔


3 posted on 02/29/2024 12:44:01 PM PST by MtnClimber (For photos of scenery and wildlife, click on my screen name for my FR home page. More photos added.)
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To: MtnClimber

>>>...that leap days like today will not be necessary, about 4 million years from now. <<<

I can’t wait......................


4 posted on 02/29/2024 12:47:57 PM PST by Red Badger (Homeless veterans camp in the streets while illegals are put up in 5 Star hotels....................)
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To: Red Badger

>>>...that leap days like today will not be necessary, about 4 million years from now. <<<

So sometime in the distant future leap days will be done away with. That would mean that someone born on the last leap year used would never have another birthday.


5 posted on 02/29/2024 12:52:06 PM PST by nomorelurker
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To: nomorelurker

They would be immortal....................


6 posted on 02/29/2024 12:55:56 PM PST by Red Badger (Homeless veterans camp in the streets while illegals are put up in 5 Star hotels....................)
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To: MtnClimber
...In 1582 Pope Gregory XIII provided the further fine-tuning that leap days should not occur in years ending in 00, unless divisible by 400....

This is both imprecise and hyperbolic. The fine-tuning was done by Aloysus Lilius. Gregory just implemented it.

7 posted on 02/29/2024 2:54:32 PM PST by threefinger
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To: MtnClimber
This Roman silver coin, a denarius, depicts Julius Caesar (left) and Venus, Roman goddess of love.

Gaius Julius Caesar claimed to be a direct descendant of Venus.

8 posted on 02/29/2024 2:54:56 PM PST by sima_yi ( Reporting live from the far North)
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To: StayAt HomeMother; Ernest_at_the_Beach; 1ofmanyfree; 21twelve; 24Karet; 2ndDivisionVet; 31R1O; ...

9 posted on 03/01/2024 11:19:47 AM PST by SunkenCiv (Putin should skip ahead to where he kills himself in the bunker.)
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