Greetings, all. I'm working on a real-time star map for a role-playing game where each star is located in its time-corrected 3d coordinates. With this, each star will be where it should be in a moment of time and not where it is observed to be. To do this, I take the proper motion of the star in RA and Dec, and the Radial Velocity and use the current distance in light years plus the date from 2000 to determine the star's position. Mathematically, this is a breeze. But, the problem comes in with the radial velocity. My game is set in 2871. As a result, stars can move a long way. This got me to thinking. The way the motion of the stars is defined, they either spiral away from Sol or spiral in. Nothing travels tangentially. No stars will ever "pass" by Sol and, anything with a negative radial velocity will, sooner or later, collide. I can see no other conclusion, given the way the data on stellar motion is provided. Is this just something we're stuck with, or is there some step I'm missing that would allow tangential travel and not every star either spinning away or spinning in to slap the Sun? Thanx!