Why Does My Gadget Say It's December 31, 1969?

If you’ve ever had the date on a cell phone or computer mysteriously switch to December 31, 1969, you may have thought it was simply random. But the reason behind this odd glitch is a nice little tidbit of computer trivia.

Unix is a computer operating system that, in one form or another, is used on most servers, workstations, and mobile devices. It was launched in November 1971 and, after some teething problems, the “epoch date” was set to the beginning of the decade, January 1, 1970. What this means is that time began for Unix at midnight on January 1, 1970 GMT. Time measurement units are counted from the epoch so that the date and time of events can be specified without question. If a time stamp is somehow reset to 0, the clock will display January 1, 1970.

So where does December 31 fit in? It’s because you live in the Western Hemisphere. When it’s midnight in Greenwich, England, it’s still December 31st in America, where users will see December 31, 1969—the day before Unix’s epoch.

So how do you fix it? Simple. Just correct the date to the present time.

Learn more about Unix from Ken Thompson and Dennis Ritchie, two of the creators of Unix:

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