The digital clock you'll see running on the Young Wizards site is keeping time according to the Julian Day system -- the preferred method of measuring Earth time for wizards living or working here. Julian dating's extreme accuracy and flexibility makes it easier to tell exactly when that crucial spell is going to start (or stop) working...or, for that matter, when you're supposed to be home for dinner. (Since "But it was only two o'clock on Pluto...!" isn't likely to get you out of trouble more than once.*)

Julian dates are unaffected by calendar weirdnesses (like leap-year days), time-zone changes (making the system useful for keeping track of time back home when you're off planet), or such strictly local and often confusing phenomena as Daylight Savings. All these factors make the JD system ideal for use by wizards on the go.

Designed by John Pritchard of Syntelos.com, the Java applet which runs our clock takes its time from your own computer -- unlike the clock in every wizard's manual, which gets it, like all other Manual content, directly from the Powers that Be or one of their delegated representatives. In Earth's case, this means a small group of wizards who determine a daily consensus "steer" or calibration of local Manual time with the overt or covert assistance of colleagues in organizations like the Royal Observatory, Greenwich, the US Naval Observatory, the European Frequency and Time Forum, and the International Bureau of Weights and Measures.

See this link for more details about the JD system and how it began.

Also, useful Julian Date calculators / converters can be found here and here.