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Re: starship-design: HIGHLY OPTIMIZED TOLERANCE
Curtis Manges writes:
> > Typical velocities of nearby stars relative to the sun are in tens of
> > km/s. The expansion of the universe is only significant on an
> > intergalactic scale; orbital motion around the galactic center dominates
> > the motions of stars in our neighborhood.
> > While you'd have to take the relative motion of your destination star
> > into account, its relative velocity is going to be pretty small compared
> > to your spacecraft's velocity if you're planning on getting there in
> > anything less than thousands of years.
> Thanks for straightening me out on that. Would I be right in guessing that
> the time scale is about similar to the precession of Earth's polar axis? I
> know Polaris wasn't always the pole star . . .
The Earth's precession is caused by tidal interaction with the Moon, and
it takes about 22,000 years for the poles to precess through a complete
circle. The rotation period of the Galaxy is something like 250 million
years. The two phenomena aren't really related.