I'm confused..???... red shift /galaxies?

Question

"WE" are not at the center of the Universe.... yet what I read says that ALL the other galaxies are moving AWAY from us..... how is that possible?.... isn't there ANY that are moving along toward us?.....

since we're in the arm of the Milky Way, I'm assuming that the stars in one of the other arms or in ours are moving toward us...yes?...

but no galaxies?... then who's overtaking who between us and Andromeda, for when we're supposed to collide?....

thanks for clearing up my fog....

Answer 1

First of all galaxies tend to cluster. The Milky Way is part of a group of about 40 galaxies. Andromeda is the largest and the Milky Way is the next largest. All the other galaxies in this local group are satellite galaxies and are/will be absorbed by the largst two. In time Andromeda and the Milky Way will merge, but not very soon. That will be in about a billion years or so.

As for the rest of the universe it appears to be expanding and all other groups of galaxies are moving away from us. Take a sheet of paper and pencil. Put about 20 to 30 dots all over the paper. The points represent other groups of galaxies. Put the paper in a xerox machine and make X2 copy. Examine at the expanded copy. The expanded copy represents the universe after it has expanded. Any point is now farther away from any other point. No matter which group of galaxies you look at they are all farther away from one another. Everyone sees everyone else as moving away.
In time (billions of years) the universe will expand (if current theories are correct) to the point where we will not be able to see distant galaxies because they are moving so far away and so fast . The only dot on your sheet of paper will be the combined local group of galaxies.

When the Milky Way and Andromeda will collide? I have heard some estimates of about a billion years and they will pass through one another several times before they finally combine, which will take several more billion years.

Your question about other stars in the Milky Way moving toward or away from us. All of the stars in our galaxy are moving toward or away from us. Their orbits however to not point directly at us. It is like standing at the train station. You can hear the train coming toward you but it is not going directly at you. It pass you by as it moves away from you. The train was coming at you and away from you without going through you. Stars do the same thing only on a much larger scale of time and distance.

Hope this helps.
D. Bumstead :)

Answer 2

First, inside a galaxy, the relative speed of the stars with respect to each other isn't very fast. Like watching the far side of merry-go-round, you see another horse in motion but it doesn't get closer or farther.

Now, with other galaxies - think about being a fragment of a hand grenade explosion. It doesn't matter *which* fragment you are - all the others are moving away from you. Some have higher velocity than others, most notibly those farther away.

With that, there *are* some galaxies moving towards us, but it's the result of gravity, and not the Big Bang. We're simply close enough to a few other galaxies that our mutual gravitational attraction has altered our courses toward each other.

Answer 3

In general, all galaxies are moving away from each other, but thay are not evenly distributed through space. They are collected into small groups of about 20-30, usually with up to about 5 large galaxies like ours and the Andromeda, with a larger number of small galaxies up to about 1/10th their size. These are held together by mutual gravitational attaction, and so some will be moving towards us and some away but this has nothing to do with the expansion of space.
Your query about stars in our local galaxy is quite a different situation. The galaxy is rotating about its centre and like all rotating objects, it rotates faster closer to the centre. This means that stars closer to the centre of the galaxy and behind us are moving towards us, and also that we are moving towards those farther out and in front of us. But those closer in and ahead of us and those farther out and behind us are moving away.
And by the way, the term 'red shift' is actually a bit of a misnomer. The light isn't shifted towards the red end of the spectrum, the wavelengths are stretched by the expansion of space. Think of it this way. A wave is laid out on a bit of elastic 1cm long and 'fastened' at both ends. The elastic is then pulled. There is still only one wavelength but the wavelength is now longer.

Answer 4

No, not *all* the galaxies are moving away from us. In fact, of the 1000 or so closest galaxies, some are getting closer and some are moving away. But after that, all these super-groups of galaxies are all all moving away from each other.

Answer 5

Cambpell P is right. And we -are- heading for a collision with Andromeda so, yes, that's one Galaxy that's moving towards ours. But it won't happen for another several billion years (I don't remember the exact number ☺)

Doug

Answer 6

All galaxies are moving away from all other galaxies. Think of a spotted balloon being blown up. All the spots get farther apart as the balloon gets bigger. From the point of view from any one spot, all the other spots are moving away from it, but in fact all the spot are just spreading out.