Formation of groups, clusters and superclusters Gravitational attraction pulls galaxies towards each other to form groups, clusters and superclusters.

It is plausible that the galaxies within our observable universe represent only a minuscule fraction of the galaxies in the Universe.

Subsequently many other observations have indicated the presence of dark matter in the universe, including gravitational lensing of background objects by galaxy clusters such as the Bullet Cluster, the temperature distribution of hot gas in galaxies and clusters of galaxies and, more recently, the pattern of anisotropies in the cosmic microwave background.

Galaxies form, and generations of stars form in those galaxies, and around one star, at least one star, is a habitable planet.

Intergalactic space takes up most of the volume of the Universe, but even galaxies and star systems consist almost entirely of empty space.

Formation of galaxies Large volumes of matter collapse to form a galaxy.

In those galaxies, you'll be able to do astrophysics, and learn the laws of physics.

And we can also study chemical composition and physical parameters of stars, galaxies, nebulae.

It is the brightest of the five main spirals in the direction of the Sculptor Group.

Tammann is a former President of the International Astronomical Union Commission on Galaxies.

But that's still not typical of the universe, because stars come in galaxies.

Evolution Interstellar clouds like the Orion Nebula are found throughout galaxies such as the Milky Way.

This galaxy group consists of the spiral galaxies M65, M66, and NGC 3628.

Such rings help in understanding the distribution of dark matter, dark energy, the nature of distant galaxies, and the curvature of the universe.

It is one of the closest galaxies to the Local Group, and probably lies between us and the Sculptor Group.

As we move out, the light from these distant galaxies have taken so long, we're essentially backing up into the past.

I have to talk about astronomy without showing you any single image of nebulae or galaxies, etc.

While it is often believed that stars only exist within galaxies, intergalactic stars have been discovered.

It is one of the largest comprehensive catalogues, as it includes all types of deep space objects and is not confined to, for example, galaxies.

The Coma Cluster (Abell 1656) is a large cluster of galaxies that contains over 1,000 identified galaxies.

The Virgo cluster lies within the Virgo Supercluster, and its gravitational effect slows down the nearby galaxies.

Note the smaller galaxies visible in the image are in the distant background they are not satellites.

Okay, let's say this is the size of the observable universe, with all the galaxies, with all the stars, okay, from here to here.

Other cluster members include NGC 1316 (the group's brightest galaxy), NGC 1365, NGC 1427A, and NGC 1404.

The larger of the spiral galaxies, known as UGC 1810, is about five times more massive than the smaller galaxy.

I mean, even the Scientologists know to start with a personality test before they start telling people all about Xenu, the evil intergalactic overlord.

But we do know that the self organization trend throughout the universe is long, and it began with things like galaxies they maintained their order for billions of years.

However, even the deep vacuum of intergalactic space is not devoid of matter, as it contains a few hydrogen atoms per cubic meter.

In this case, what we take to be very distant galaxies may actually be duplicate images of nearby galaxies, formed by light that has circumnavigated the Universe.

On 16 June 2008 NASA's Galaxy Evolution Explorer project reported finding large numbers of new stars in the outer reaches of the galaxy.

And we hope to be able to test some of Einstein's theories of general relativity, some ideas in cosmology about how galaxies form.

And if we are interested, for example, in the fact that anti gravity is pulling galaxies away from the Earth, why should we not be interested in what is going on inside of human beings?

Stars can be much closer to each other in the centres of galaxies and in globular clusters, or much farther apart in galactic halos.

Second, we've been able to look at that interaction of how supermassive black holes interact, and understand, maybe, the role in which they play in shaping what galaxies are, and how they work.

And so as we move out, we see continuously from our planet all the way out into the realm of galaxies, as we see here, light travel time, giving you a sense of how far away we are.

They're the ones that are embedded in that sea of dark matter that are causing the bending of the light to cause these optical illusions, or mirages, practically, of the background galaxies.

If you could do this, what you would find that with each passing day, each passing year, each passing billions of years, OK, the distance between galaxies is getting greater.

I want her to look at the world through the underside of a glass bottom boat, to look through a microscope at the galaxies that exist on the pinpoint of a human mind, because that's the way my mom taught me.

Some ultra luminous X ray sources (ULXs) in nearby galaxies are suspected to be IMBHs, with masses of a hundred to a thousand solar masses.

It has been used in conjunction with observations from the Hubble Space Telescope to determine the relative motions of the Local Cluster of galaxies within the Local Supercluster.

Dark energy, on the other hand, is putting more and more space between the galaxies, makes it, the gravitational attraction between them decrease, and so it impedes the growth of structure.

Maybe the reason for thr creation of the universe, and all the galaxies, and all the planets, and all the energy, and all the dark energy, and all the rest of stuff is to create what's in this room.

I've often wondered, what is the evolutionary pressure that made our ancestors in the Veldt adapt and evolve to really enjoy pictures of galaxies when they didn't have any.

Well, again, it's dark out there to human senses. But all you've got to do is take a telescope, even one of present day design, look out and you'll see the same galaxies as we do from here.

So, recently, we have realized that the ordinary matter in the universe and by ordinary matter, I mean you, me, the planets, the stars, the galaxies the ordinary matter makes up only a few percent of the content of the universe.