Calendars on other worlds

On the Earth, the time and date is pretty easy to figure out. But what about on other worlds? There is next to no chance that the days on another planet will be 24 hours long and even less chance that their years would be 365.25 days long.

The solution: two calendars. One local and one "universal" calendar, keyed to Earth of course. Not that the Julian calendar is all that logical but you have to start somewhere.

Say that today is January 21st, 2013 at 1:05:24 PM GMT. We would define Universal Time (UT) as 20130121.01.05.24. One second later, it would be .25 then .26 and so on.

The local calendar can be tailored to the particular planet's rotational period and orbital period around its primary star.

Can this work? It already does, here on Earth. For example, there is the Jewish Calendar which is lunar-based (as is the Muslim calendar) yet all Jewish people know the Julian calendar date. We all know about the Mayan calendar. Time is time and already measured against GMT.

Even if everybody accepted this, when you get to where you are going, your UT clock will be off. If you travel faster than light, who knows what it will read? It could even go backwards. If you travel slower than light but still at relativistic velocities, you will experience time dilation and your clock will run slower.

The solution? Find an astral object with predictable properties. Say it is a quasar that flashes with a certain periodicity or a star whose brightness is diminishing by an infinitesimal amount. Whatever it is, certain markers will be tied to UT so that whenever you get to where you are going, you can set your UT clock by the stars.

Your local clock? Good luck with that. On a planet whose orbit takes only 180 days, people would live to be 140 years old easily, local time. But UT would still give us a way to tell their actual age. People-years, dog-years, it'd all be predictable and calculable.