Okay I don't really know where to put this because it's not really physics and all, so I'm leaving it here. Also apologies if this sounds weird or if the physics is just plain wrong, it's 2.30 AM in the morning where I am and I didn't want to forget it when I woke up. Suppose that at some point in the distant future, Mankind manages to assert an interstellar presence (by conquest, diplomacy or otherwise). Suppose that we limit ourselves to the Milky Way because we're lazy. After the bloodthirsty warriors/filthy politicians/Carl Sagan finish whatever it is they're doing to get their name(s) into history books, the ISO bureaucrats begin to bemoan the need for a new system of spacetime coordinates since obviously lat/long/alt/unix epoch, being quite Earth-specific, don't quite cut it any more. Standardised time seems the more difficult issue to handle, really. A Star Trek style Earth-based stardate *might* work for interplanetary colonisation, but would certainly fall down on an interstellar scale. At large distances, special relativistic effects become non-negligible. The administrative hassle is exacerbated by lots and lots of mutually moving reference frames, assuming that we populate more than one star system (since it is rare that any two given star systems are always at rest with respect to each other), lots and lots of non-inertial reference frames (because planets orbit stars and stars orbit the galactic core and orbiting means acceleration) different gravitational time dilation effects (because not everyone will live on a http://memory-alpha.org/en/wiki/Class_M" [Broken] orbiting a G2V yellow star at the same distance from those nasty black holes at the galactic core as the Sun) That's not even counting the fact that travelling between star systems would take very very long (probably even from the travellers' reference frame, despite time dilation), nor the fact that people who are moving at high speeds still need a way to maintain standardised time (because that's what standards are for). Compared to this, locating yourself within the galaxy seems almost trivial. One could conceivably conjure up, say, a cylindrical coordinate system (treating the centre of Earth as phi = 0) and arbitrarily assign a positive h and phi direction. Or at least that's how I would like to do it. It seems like the most natural way to do it for a roughly pancake-shaped object, after all. Thoughts, anyone?