Allocates a Date object and initializes it to represent the specified number of milliseconds since the standard base time known as "the epoch", namely January 1, 1970, 00:00:00 GMT.So it's simply a standard that's commonly used in the computer industry.
It would be interesting to know how dates like 1582-10-15 and 1858-11-17 were chosen.Platform Epoch
OpenVMS Alpha 1858-11-17
It would be interesting to know how dates like"Originally, the COBOL programming language did not come with built-in time and date functions. However, since Y2K new functions have been introduced using integer dates, although with two different epochs. ANSI dates use 1601-01-01 as day 1. Lilian dates use 1582-10-15 as day 1"
and 1858-11-17 were chosen."The OpenVMS Alpha operating system counts intervals of 100 nanoseconds since the Modified Julian Day epoch, 1858-11-17, 00:00:00.00 UTC. However, it is only incremented every 10 milliseconds, 100,000 intervals (10,000,000 ns) at a time. OpenVMS VAX (formerly VAX/VMS) uses the beginning of the current year as the epoch."
I also seem to remember that it also permitted datesStar date is the Julian Calendar, AFAIK. Something like 43243.5 - midnight of some day number 43243. In order to use smaller numbers, they modified it and substract about 4000 years worth of days. I guess NASA et. al. still use the modified JC.
as far back as October 22, 4004 BC and no further :-)