Leap Year

February 28, 2012

Fun Facts for 2012

There are 3 "Friday-the-13ths" in 2012, 13 weeks apart from each other.  Also, Friday falls on the 13th more often than any other day of the week!

Source:  Skymaps.com   The Evening Sky Map   January 2012

http://www.skymaps.com/downloads.html

Happy Leap Day!  Every four years, we get to experience something unique that became a part of our culture specifically because of Earth's orbit around the Sun.  Although this event seems to happen every four years, sometimes we skip a year.

If you look at the night sky, you'll notice that the constellations that you saw last year at this time are in exactly the same place.  Did you know that if you went outside at midnight on your birthday every year, you'd see exactly the same star patterns?  The planets and Moon would all be in different positions each year, but the stars appear to be in the same place.

Every four years, we have to add one whole day to our calendar to make sure that the star patterns you see on your birthday are exactly the same, year after year.  This is because the time it takes for the Earth to travel around the Sun doesn't exactly match our calendar year.  It takes approximately 24 hours for the Earth to rotate once on its axis.  That's one day.  And it takes almost 28 days for the Moon to orbit the Earth.  That's one month.

But a year is how long it takes for a planet to travel all the way around the Sun and return to the same spot.  It takes Earth approximately 365 days, 6 hours to travel around the Sun once.  Over time, this extra six hours started causing problems for our calendar, because after a few decades, timekeepers noticed that we were almost a week behind in our journey around the Sun than where we should have been according to our calendar.  So what did they do?  They added extra time to the calendar to compensate.  And since we're off by 6 hours a year, every 4 years we'd be almost an entire day behind where we should be (according to our calendar).  Since 6 hours each year for 4 years adds up to 24 hours, it was decided that the simplest way to fix things was to add an extra day to the calendar every 4 years.

Years when we do this are called Leap Years and the day we add to our calendar count is called a Leap Day.  Now where should we put it?  February has the least number of days--let's add it to February and we'll come up with February 29th.

We traditionally experience a Leap Year in years that are evenly divisible by 4; like 2008, 2012 and 2016.  However, when a century ends, we skip a leap year. The exception is if the century ends on a year that is exactly divisible by 4.  So 1800 and 1900 weren't Leap Years, but 1600 and 2000 were Leap Years.  Going forward in time, 2100, 2200 and 2300 won't have a Leap Day but 2400 will.

The reason the 'end of century' rule was introduced is because the correction is too big.  The 6 hours is actually rounded up from 5 hours, 49 minutes and 16 seconds!

Treasure your extra day this year!

Source:  JH STAR GAZER HOME PAGE

http://www.jackstargazer.com/scripts0SG1209.html

The phase of the Moon on Leap Day is First Quarter.

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