Reply to Henk

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Henk wrote to sci.astro.research -


as a layman I'm interested in the universe.


My question is:


If I shoot (by an imaginairy explosion) an imaginairy galaxy system X
from
Earth into some direction into space with a speed that causes that
galaxy X
having the same redshift as a galaxy B who's redshift suggests it's at
a
distance of 13 Billion lightyears from Earth, will the relative speed
between galaxy X and galaxy Y be zero? Or is this a wrong way of
thinking,
because galaxy X is MOVING THROUGH the expanding space while galaxy Y
is
('stationary' in, and) PART OF the expanding space?


Regards,


Henk

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To Henk

To become comfortable with the motion of galaxies distant from our own
Milky Way you begin with the motion of planets in our own neighborhood
and especially the retrograde motion of Mars.

http://alpha.lasalle.edu/~smithsc/Astronomy/retrograd.html

Retrograde motion is a consequence of the heliocentric motions of Mars
and Earth as we watch the orbit of our position change in relation to
the orbit of Mars going around the Sun.

If you become familiar enough with that heliocentric perspective,move
on to the next motion - the galactic orbital motion of the Earth /solar
system along with the rest of the local visible stars around the Milky
Way axis.In principle we know that the local stars are rotating about
the galactic axis because ,over time, they will change their
orientation to the remaining galaxies just as if we are on an enormous
carousel made of stars.

Designating the position and motion of galaxies to local stars and
consequently the true motion of galaxies to our own will rely on the
explosive supernova events and Ole Romer's insight on the correction of
position and motion due to finite light speed but unfortunately
astronomy is still stuck with the Newtonian celestial sphere format
expanded into relativistic homocentricity ,the 'every valid point is
the center of the universe' notion.

.

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