Now, first remember about the redshift space.

So, we're not in a uniquely hospitable place.

Galaxies

Start differentiating into effector and memory cells.

A different way to measure that, would be from the x ray gas they contain.

Galaxy

galaxy

galaxy cluster

Galaxy

The Coral Galaxy!

Well, this is a picture of it.

Galactic Coordinates

Gal. long.

Gal. lat.

But not too little.

(Laughter)

Virgo cluster, but most of them are tiny dwarfs that you have difficulty actually pointing out.

Galactic Conquest

And those smudges we see in the night sky?

Ammunition loader on intergalactic runs.

There is one important distinction though, the early type galaxies, ellipticals and S0s tend to concentrate in clusters more than in general field and there is relatively few spiral galaxies in clusters.

Our location is saturated with evidence and also with matter and energy.

with easy solutions around.

Because of the dense environment both proximity of many other galaxies to zip by or merge with and the dense intergalactic medium of x ray gas.

On the other side is Perseus Pisces

And this is an example of a very, actually, famous cluster, the Coma cluster.

So where does the gas come from?

Galway

Galactic Strategy KDE Game

So, let me give you the two examples.

Milky Way and Andromeda are the two dominant galaxies in the group and there is a large number of their dwarf galaxy satellites.

This plot is centered on a local group of galaxies, but really, the center of the Local Supercluster is at Virgo.

Most of them have super massive black holes in the centers.

But the dominant component, of course, is the dark matter.

And things may acutally go even beyond that.

The Andromeda Galaxy is my home.

Think of DNA, cells, galaxies, fruits,

This was noted as an elegant structure in the sky and that we are kind of in its plane.

So for now, let's turn to the evidence for dark matter.

So, this is what Toomre and Toomre saw. And in fact this explained many puzzling observations.

Now, if we plug in typical numbers, say, for extent of dark halos of galaxies and sizes of clusters of galaxies, we find out that the relative collapse times are a few hundred million years for galaxies and few billion years for clusters.

As we look deeper, we find more clusters and by and large, some of them look pretty much like clusters near us.

And here's a beautiful picture of the Andromeda Nebula, which is our closest, largest spiral galaxy to the Milky Way.

When we look out into space, we see stars and galaxies.

If you can map all of the distorted images, you can, in principle, reconstruct the distribution of mass that led to the