Explain what the open dating system is
Since 1900 is incorrectly treated as a leap year in these systems, January 0, 1900 actually corresponds to the historical date of December 30, 1899.Computers do not generally store arbitrarily large numbers.Software timekeeping systems vary widely in the granularity of their time units; some systems may use time units as large as a day, while others may use nanoseconds.For example, for an epoch date of midnight UTC () on January 1, 1900, and a time unit of a second, the time of the midnight () between January 1 and 2, 1900 is represented by the number 86400, the number of seconds in one day.The People's Republic of China adopted the common era calendar in 1949 (the 38th year of the Chinese Republic).In astronomy, an epoch is a specific moment in time for which celestial coordinates or orbital elements are specified, and from which other orbital parametrics are thereafter calculated in order to predict future position.Stale statistics can cause the optimizer to choose a less-than-optimal plan for executing a query.The query plan that the EXPLAIN statement creates contains information about statistics.
Such calculations generally result in an elliptical path on a plane defined by some point on the orbit, and the two foci of the ellipse.
The "epoch" then serves as a reference point from which time is measured.
Time measurement units are counted from the epoch so that the date and time of events can be specified unambiguously.
Viewing from another orbiting body, following its own trace and orbit, creates shifts in three dimensions in the spherical trigonometry used to calculate relative positions.
Interestingly, these dynamics in three dimensions are also elliptical, which means the ephemeris need only specify one set of equations to be a useful predictive tool to predict future location of the object of interest.
Epochs are generally chosen to be convenient or significant by a consensus of the time scale's initial users, or by authoritarian fiat.