"Tim Killian" wrote in message
...
But if we're to believe the cosmologists, stars only represent about 1%
of the total matter. Another 4% is interstellar gas and neutrinos, and
the remaining 95% is Unobservium. Deep thinkers and mathematicians tell
us Unobservium is made up of 23% dark matter, and 72% dark energy. The
dark matter cannot be observed, but it supposedly has profound
gravitational influence. And the all-important dark energy is crucial as
it fills an empty spot in the curvature equations.

So your stellar "spheres of influence model" must be adjusted
accordingly. As we sit here today, a lump of dark matter may be tugging
at ol' Sol's happy little orbit, or stirring the Oort cloud into mischief!

If the background mass is more or less uniformly distributed, it will
not influence the spheres of influence (so to speak) of the "point source"
stars. If something substantial was tugging differentially on Sol, it would
have shown up in the Hipparcos results, no?


Personally, I'm a little skeptical of the latest theories. I prefer the
traditional model where the universe is carried on the back of a rather
large turtle.

:-)