Now, I know it has to do with the alignment of the Calendar - but other than that I know nothing!  If you are like me, no worries!  I did the research for you!  According to Chiff.com ....

  • It was the ancient Egyptians who first figured out that the solar year and the man-made calendar year didn't always match up.
  • That's because it actually takes the Earth a little longer than a year to travel around the Sun -- 365 days, 5 hours, 48 minutes, and 46 seconds, to be exact.
  • Therefore, as the hours accumulated over the centuries, an extra day was occasionally added to the calendar, and over time the practice became more or less official.
  • The Romans first designated February 29 as leap day, but a more precise formula (still in use today) was adopted in the 16th century when the Gregorian calendar fine-tuned the calculations to include a leap day in years only divisible by four - 2012, 2016, 2020, 2024, etc.
  • Leap years occur every four years -- except those ending in double zeros, such as 1900 and 2100, said Geoff Chester, a spokesman for the United States Naval Observatory. To confuse matters, there is an exception to that exception: Years ending in double zeros that can be evenly divided by 400, such as 1600 and 2000, are in fact leap years.

So there you have it!  Anyone less confused then they were before??