Space is a little different than something like dungeons & dragons in that objects in space are continuously moving, so a D&D explanation of the position of a building ("it's beside town hall") doesn't work for planets in relation to each other or the moons of a gas giant. Visiting Alpha Centauri in the now vs 6 months from now might have a gas giant in easy reach on ingress or on the other side of the system. The next destination could be either shadowed by the star, requiring a much longer egress to get line of sight clear for the next target or it could be a straight flight out, again, depending on the time of year, or you want to describe a circumstantial asteroid flyby relative to the player's ship: https://i.imgur.com/uoV9tib.gifv , or describing the orbit change of the asteroid that occurred from that encounter https://i.imgur.com/51Snazi.png . It can (possibly) contribute to the sensation that the universe is continuing to happen, even when the players aren't around. You can throw in that the players celestial engineering, such as maneuvering a comet so that it will occasionally visit the inner system, inadvertently created a religion on the TL0 civilization on the planet in system, and you can accurately describe the motion of the holy star in the sky. You can do that without any celestial mechanics but the mechanics are easy and it allows for consistency over a long period of time. 

Also, if you place some of your adventures in close orbit around a black hole, even 6G acceleration over a period of days may not significantly change your orbit, and traditional orbital mechanics becomes useful in gameplay again. 

Obviously, Traveller largely went in a completely different direction in general, but I'm always hopeful that there are a few others out there that make an attempt to harden their Traveller games to physical reality a bit more. 



-------- Original Message --------
On January 20, 2018 10:33 PM, Tim <xxxxxx@little-possums.net> wrote:

I've never described (or even generasted) orbital parameters for
objects in a Traveller game like that, any more than I would describe
a building's location in terms of surveying markers.
 
It's assumed that any competent astrogator does understand such
specifications (and more) in universe, but the players certainly
don't. For that sort of orbit, I would normally describe it as just a
highly inclined, slow orbit a few diameters out from the planet. If
they wanted more information (e.g. orbital period), I could estimate
it on the fly (e.g. "about an Imperial day"), or compute it in more
detail if it was important.
 
However, I would much more likely start with the relevant facts about
the orbit, and generate some numbers later if necessary. It has
almost never been necessary.