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Originally posted by OMsk3ptic
Our two galaxies are close enough that the gravitational force is greater than the force causing expansion. At least I think that's what the explanation is.
The Andromeda Galaxy (M31) is the closest spiral galaxy to us, and though it’s gravitationally bound to the Milky Way, it’s not the closest galaxy by far, being 2 million light years away. The Large and Small Magellanic Clouds are two irregular dwarf galaxies about 180,000 and 210,000 light-years away, respectively. They were thought to be orbiting the Milky Way, but that may not be the case.. All of these galaxies make up part of what is called the Local Group, which is a group of more than 30 galaxies that lie within 4 million light years of the Milky Way. Read more: www.universetoday.com...
As you discovered, in fact the galaxies are NOT all moving away from each other. What is actually happening is that galactic clusters are moving away from each other. The Milky Way, Andromeda, and over 30 other galaxies are part of the same galactic cluster. The gravitational forces within a galactic cluster are stronger than dark energy forces within that cluster which is why Andromeda is moving toward rather than away from us.
Originally posted by jiggerj
Several times I've read and heard that all the galaxies are moving away from each other. The way this is occurring is that the space between the galaxies is filling in with dark matter, thereby pushing all the galaxies further and further away from each other.
Question: What's wrong with the dark matter that's supposed to be filling in the space between the Milky Way and the Andromeda galaxy? Why are we on a collision course instead of being pushed away?
The Universe is expanding and galaxies are racing away from each other, as indicated by their redshifts. The further they are, the faster they are receding. But, on a more regional scale we find that galaxies tend to cluster together, drawn toward each other through the relentless pull of gravity. The spectra of these galaxies measured from within the cluster will show a blueshift, indicating that they are moving toward each other.
Originally posted by Arbitrageur
But, on a more regional scale we find that galaxies tend to cluster together, drawn toward each other through the relentless pull of gravity. The spectra of these galaxies measured from within the cluster will show a blueshift, indicating that they are moving toward each other.
Also, I think you meant dark energy, not dark matter, which is why I referred to dark energy.edit on 1-10-2012 by Arbitrageur because: clarification
Originally posted by jiggerj
Thank you! I didn't know that.
And, I'll never get Dark Energy and Dark Matter right.