This calendar is quite 'user-friendly'.Just input the month number that you want (1 through 12), then input the year (anything after 1600). When you click 'CALCULATE', the entire month will be displayed.
INSTRUCTIONS
Just for fun, input February, 1900. What happened? It's NOT a Leap Year? Did the folks
at 1728 Software Systems 'foul up'? Heck no! Just read the next section.
LEAP YEAR INFORMATION
The 'modern' calendar is based upon the amount of time it takes the Earth to
go through one seasonal cycle (called a 'Tropical Year' - about 365.25 days).
More than 2,000 years ago, the Romans were aware of this and made every
fourth year have 366 days which was accurate enough for a timespan of a few
centuries. The Romans (and earlier the Greeks) were even aware that the tropical
year was slightly Other countries eventually compensated for this and a new calendar rule was adopted. Every 4th year would still be a Leap Year with special exceptions for certain "Century Years" (1700, 1800, 1900, etc). If such a year is divided by 400 and has no remainder, then it will be a leap year as is the case with 2000 and 2400. If there is a remainder, then it will only be a 365 day year as is the case with 1700, 1800, 1900, 2100, etc. You may test this by inputting February for these years.
JULIAN DAYS
Are you wondering what JD, MJD and TJD are?
Modified Julian DaysHere the 'zero' point is November 17, 1858 at MIDNIGHT. (or expressing it mathematically - Modified Julian Day Number = JD# -2,400,000.5). Now there were fewer digits to deal with and the day changed at midnight just as it does in the civil calendar in common use today. Still another system was introduced called:
Truncated Julian DaysHere the zero point is May 24, 1968 at MIDNIGHT. (Expressed mathematically, TJD = MJD# -40,000 and TJD = JD# -2,440,000.5).
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