Today is leap Year Day
which means that the Earth's rotation around the sun--

of course the basis for our year--

doesn't quite fit into an exact whole number of rotations of the earth about its own axis

which is our day.

In fact a year takes rather close to 365 1/4 days,

but not quite--- so after the leap year correction every four years there's still about 11 minutes too much overcorrection , which is adjusted by skipping leap year days occasionally-- and then not --

and that isn't exactly right either----

so a bit more a bit more finagling will have to take place every few thousand years to fix that.

For more details see the excellent article below.

Hzl

2/29/16

PS: But I also believe I read somewhere that the Earth's rotation is slowing down because of the effect of the moon 's gravity (and our tides):

The Moon slows the Earth's rotation, but how fast was it ...

curious.astro.cornell.edu/...earth/147-the-moon-slows-the-earth-s-rotatio...

Jul 18, 2015 - In a previous answer you said: "The Earth's rotation is slowing down because of this [the Moon pulling back on its tidal bulge]. One hundred years from now, the day will be 2 milliseconds longer than it is now." I've seen numbers for the Moon's formation from 4 to 4.6 billion years ago.

Tidal acceleration - Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Tidal_acceleration

Wikipedia

First there is a real retardation of the Moon's angular rate of orbital motion, due to tidalexchange of angular momentum between Earth and Moon. This increases the Moon's angular momentum around Earth (and moves the Moon to a higher orbit with a lower orbital speed).

Why is Earth rotating? Did it always have the same rotation ...

spaceplace.nasa.gov/review/dr-marc-earth/earth-rotation.html

NASA

Earth's graceful 24-hour rotation rate is one of the traits that makes our planet so ...The cloud began to collapse, flattening into a giant disk that rotated faster and ... thetides and the turning Earth, causing the rotation to slow down just a little.

One hundred years from now our day will be "2 milliseconds longer than it is now". due to this effect. So in a million years that will amount to

about a half hour and a bit more tinkering will be needed but we can worry about this later..... and

PPS: All that is probably enough to consider without worrying about Sadie Hawkins Day too!

52°

Clear Sky

Comment

Leap Year is tomorrow, but do you know why?

Posted: February 28, 2016 - 12:01am

BY LAURA J. MCKENZIE GUEST COLUMNIST

A year is 365 days long … well, sort of … except when it’s not.

A year is the time it takes the earth to go around the sun one time. In reality, it takes 365 days, 5 hours, 48 minutes and 45 seconds to make that trek.

It’s called a “tropical year” which results in time being “off” by about one day every four years if you want to keep your seasons and holidays figured correctly.

Don’t get your sunglasses and swimwear out yet – instead it’s time for a toga party.

While the Egyptians were among the first to calculate the need for a leap year, “time” didn’t change until about 46 B.C., according to Evan Andrews in an article published for History.com. It turns out that the Roman general Julius Caesar, with the guidance of astronomer Sosigenes, introduced the first Leap Year about 2,000 years ago to adjust for those 5 hours, 48 minutes and 45 seconds.

Caesar simply ruled that any year evenly divisible by four would be a “leap year”. This became known as a “Julian calendar”.

Except there was a problem. Simply adding a “leap day” on years divisible by four created an extra .242 day (11 minutes) each year. This created too many leap years. Every 128 years, time was “off” again by a whole day. By the time the 14th century rolled around, the calendar was 10 days off the solar year, according to Andrews.

ENTER THE POPE: Pope Gregory XIII instituted a revised “Gregorian Calendar” in 1582. His calendar takes more math.

According to sources, in the Gregorian calendar three criteria must be taken into account to identify leap years:

• The year can be evenly divided by 4;

• If the year can be evenly divided by 100, it is NOT a leap year, unless;

• The year is also evenly divisible by 400. Then it is a leap year.

This means that in the Gregorian calendar, the years 2000 and 2400 are leap years, while 1800, 1900, 2100, 2200, 2300 and 2500 are not leap years.

Still, it isn’t a perfect formula. The Gregorian calendar is 27 seconds too long, so it is off by 1 day every 3,236 years, according to sources. “Experts note that the remaining discrepancies will need to be addressed in around 10,000 years,” noted Andrews.

“The name ‘leap year’ comes from the fact that while a fixed date in the Gregorian calendar normally advances one day of the week from one year to the next, the day of the week in a leap year will advance two days (from March onwards) due to the extra day added at the end of February (thus leaping over one of the days in the week). For example, Christmas fell on Tuesday in 2001, Wednesday in 2002, and Thursday in 2003 but then leapt over Friday to fall on a Saturday in 2004,” according to Wikipedia.

People born on February 29 – Leap Day – generally celebrate their birthdays either on Feb. 28 or March 1. There is one special tradition on Leap Day and it involves marriage.

BACHELORS, BEWARE: According to timeanddate.com, February 29 became a day to break tradition for marriage proposals. Women could ask their heart’s desire for their hand in marriage. If he refused, then he had to buy her 12 pairs of gloves to hide her embarrassment of not having an engagement ring.

READY, SET, SADIE: Back in 1937, cartoonist Al Capp was popular for his Li’l Abner strip about a hillbilly community called Dogpatch, according to Wikipedia. Sadie Hawkins was a character who was the daughter of one of Dogpatch’s earliest settlers, Hekzebiah Hawkins. As the ‘homeliest gal in all them hills”, she remained a spinster until the age of 35. Both father and daughter grew frantic.

“Hekzebiah called together all the unmarried men of Dogpatch and declared February 29 as ‘Sadie Hawkins Day’. A footrace ensued and whomever Sadie caught was to be her husband. “With matrimony as the consequence of losing the foot race, the men of the town were literally running for their freedom,” states Wikipedia.

While Sadie didn’t “catch” the man she had her eye on, the race did result in her marriage.

Capp further cartooned the spinsters of Dogpatch liking the idea so much, they turned Sadie Hawkins Day into an annual event. “If a woman caught a bachelor and dragged him, kicking and screaming, across the finish line before sundown – by law he had to marry her,” states the article.

The idea caught on and became a “cultural phenomenon” with Sadie Hawkins Day dances generally celebrated on Leap Day. The gals get to do the asking to the party.

Leap Day is on the calendar for tomorrow.. Check your calendars – Tropical, Julian or Gregorian. But, if a gal asks a fella to participate in a Sadie Hawkins Day race … run!

Sadie Hawkins Day: Leap Years Historically for Women to ...

newsfeed.time.com/.../get-ready-ladies-leap-day-is-also-sadie-hawki...

Time

Feb 29, 2012 - Get Ready, Ladies: Leap Day Is Also Sadie Hawkins Day. By Melissa ...Leap Day. How should you celebrate this once-in-four-years occasion?

Sadie Hawkins Day? No. - Leap Year Day

www.leapyearday.com/content/sadie-hawkins-day-no

is already Leap Day, and Sadie Hawkins Day is already November 15. ... colleges holding Sadie Hawkins Day events in 1939, only two years after its inception.

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