Does a galaxy move?

On Thu, 15 Jan 2004 14:03:16 +0000, Odysseus wrote:

Dat's Me wrote:

Out of the blue thought: Is it possible that either Andromeda or the
Milky Way originated in another Galactic Cluster & was ejected for
whatever reason & thats why they are now on a collision course?

There's no evidence at all that our Galaxy and M31 are "on a collision

Spoilsport! :-p

course". We can measure the velocity of approach in the radial direction,
but we have no means of measuring lateral velocities. So the two galaxies
*might* eventually collide, but until we've had the opportunity to make
precise observations for perhaps a few thousand years more it's anybody's

After reading a message a bit further down the thread, I might ask the
question again in a decade or so, if I remember.

escape the other members' gravity. Here's a map of the 'neighbourhood' out
to twenty million light-tears:

http://www.anzwers.org/free/universe/galgrps.html.

Thank you for that - I don't suppose anyone knows of a url where I can
look at similar maps from different POV's?

On Thu, 15 Jan 2004 20:02:29 -0500, nightbat wrote:

nightbat wrote

And to answer Dat"s Me's question, yes, two galaxies can collide, just
like any other space body in gravitational outer space free fall. Thank
your lucky stars that the cosmos is as big as it is otherwise it wouldn't
be just called chaotic but there goes the neighborhood again!

I had come across the concept of colliding galaxies before, "E. E. 'Doc.'
Smith's Lensman" series, only there it was Milky Way & Lundmark's Nebula -
I originally thought (when writing the post that started this tread) that it
M/Way and Andromeda and had a paragraph half written before I decided to
double check. It was suggested in that book that the two galaxies passed
through each other & that populated them with planets.

"Passero" wrote in message
...
Perhaps a stupid question but i'm new to astronomy and i would like to
know
if a galaxy moves or not and if it moves, how does it move? I mean, the
planets are moving around a sun so does a galaxy move around something or
does it just move because of the big bang or what?

Along with all the other replies to this thread, an interesting thing to
consider is that a galaxy is such a large object that the light from its
different parts are reaching us quite far apart.

For example, say the Andromeda galaxy is 2 million light years away, and
100,000 light years across or so, then when we look at it, and think of it
as a snapshot in time, we're really seeing a layered progression of
thousands of years across it. And it's rotating as well. I don't know
how much a galaxy rotates in 100,000 years, but the furthest away mass of
stars we see in it wouldn't be in the same position relative to the closer
ones, if you were actually in that galaxy.