<p><a href="http://upload.wikimedia.org/wikipedia/commons/0/0f/Earth%27s_Location_in_the_Universe_SMALLER_%28JPEG%29.jpg">Here</a> is an overview of different scales we may look at the universe. On scales beyond it's almost homogeneous, and we get at the border of the visible universe. Many detailed images are available, e.g. from the <a href="http://www.nasa.gov/mission_pages/hubble/multimedia/index.html#.UzwUl6h_uqh">Hubble Space Telescope</a>.</p>

<p>If you need a three-dimensional description of the universe, your program will probably need to read portions of star, cloud, star cluster or galaxy catalogs, similar to a planetarium software.</p>

<p>The general structure of the universe, and its contents may be summarized the following way: </p>

<ul>
<li>The <a href="http://en.wikipedia.org/wiki/Observable_universe">observable universe</a> has a diameter in the order of 10s of billions of lightyears; it depends on which of the several <a href="http://en.wikipedia.org/wiki/Distance_measures_%28cosmology%29">notions of distance</a> is chosen. For distances below a few hundred million lightyears the notions get similar.</li>
<li>The universe is about 13.8 billion years old, started as a hot and dense state (Big Bang), expands, and is almost 3-dimensional Euclidean plus one time dimension on large scales; that kind of space plus time is called a <a href="http://en.wikipedia.org/wiki/Minkowski_space">Minkowski space-time</a>. Its average temperature is now near 2.7 K; we can detect a background of this temperature as <a href="http://en.wikipedia.org/wiki/Cosmic_microwave_background">cosmic microwave background</a> (CMB); the CMB is thought to be the redshifted afterglow of its state as hot plasma at 380,000 years after the Big Bang.</li>
<li>The universe mainly consists (according to current models) of <a href="http://en.wikipedia.org/wiki/Dark_energy">dark energy</a> (about 70%); that's invisible; dark energy is thought to be equally distributed, although this is going to be investigated in more detail.</li>
<li>Most (about 63%) of the matter is cold (slow) and "dark", but not equally distributed. <a href="http://en.wikipedia.org/wiki/Dark_matter">Dark matter</a> is thought to form large halos around galaxies and galaxy clusters. It's invisible and interacts via gravity with ordinary matter. It can be inferred from <a href="http://en.wikipedia.org/wiki/Gravitational_lens">gravitational lensing</a> and the velocity distribution of stars within galaxies.</li>
<li>Much of the remaining matter consists of hot (fast) <a href="http://en.wikipedia.org/wiki/Neutrino">neutrinos</a>; they are very hard to detect, but they can be detected, and they can be inferred from nuclear decay measurements.</li>
<li>Part of the energy of the universe consists of photons (e.g. radiowaves, light, x-rays, gamma rays, magnetic and electric fields).</li>
<li>A minor part (about 5%) of the universe consists of atoms and ions (simplified called <a href="http://en.wikipedia.org/wiki/Baryon#Baryonic_matter">baryonic matter</a>); that's the kind of matter we know from our immediate experience.</li>
<li>About half of the baryonic matter in the universe is thought to be the <a href="http://en.wikipedia.org/wiki/Warm%E2%80%93hot_intergalactic_medium">intergalactic medium</a> made of a rarified plasma, consisting of hydrogen atoms, protons, electrons, helium ions. It's thought to form huge filaments around <a href="http://en.wikipedia.org/wiki/Void_%28astronomy%29">voids</a> of roughly 100 million light years diameter.</li>
<li>The filaments connect and embed galaxy <a href="http://en.wikipedia.org/wiki/Supercluster">superclusters</a>. Our local galaxy group is part of the <a href="http://en.wikipedia.org/wiki/Virgo_Supercluster">Virgo supercluster</a>.</li>
<li>Galaxy superclusters are made of <a href="http://en.wikipedia.org/wiki/Galaxy_cluster">galaxy clusters</a> (diameter up to about 30 million lightyears), like the <a href="http://en.wikipedia.org/wiki/Virgo_Cluster">Virgo cluster</a>, and <a href="http://en.wikipedia.org/wiki/Galaxy_group">galaxy groups</a> (diameter up to about 10 million lightyears), like the <a href="http://en.wikipedia.org/wiki/Local_Group">Local Group</a>. Sometimes an intermediate grouping (between supercluster and cluster) like a galaxy cloud is defined.</li>
<li>Galaxy clusters contain up to about 1000 galaxies, galaxy groups less than 50. Galaxies may have sizes about 100,000 lightyears across, and consist (besides a halo of dark matter) mainly of <a href="http://en.wikipedia.org/wiki/Interstellar_medium">interstellar gas and dust</a>. After galaxy collisions this gas may be consumed by star formation or removed from the galaxy. A galaxy typically contains billions of stars. Interstellar gas of different temperature is distinguished.</li>
<li>Galaxies can contain stars across the <a href="http://en.wikipedia.org/wiki/Hertzsprung%E2%80%93Russell_diagram">Hertzsprung-Russel diagram</a>, neutron stars, black holes, sometimes supernovae, and <a href="http://en.wikipedia.org/wiki/Rogue_planet">rougue planets</a>, probably also smaller rocks ejected from planetary systems. Stars can be grouped to binary, ternary or larger systems of stars up to open and <a href="http://en.wikipedia.org/wiki/Globular_cluster">globular star clusters</a>. Globular clusters are usually old, located in the halo of a galaxy, and contain up to about a million, mostly old stars, may be with a black hole (<a href="http://en.wikipedia.org/wiki/Intermediate-mass_black_hole">IMBH</a>) in their center. <a href="http://en.wikipedia.org/wiki/Open_cluster">Open clusters</a> are mostly young and in the <a href="http://en.wikipedia.org/wiki/Disc_%28galaxy%29">galactic disk</a>. A couple of different galaxy types are distinguished, e.g. <a href="http://en.wikipedia.org/wiki/Elliptical_galaxy">elliptical</a> and <a href="http://en.wikipedia.org/wiki/Spiral_galaxy">spiral galaxies</a>. Dense <a href="http://en.wikipedia.org/wiki/Molecular_cloud">molecular clouds</a> may be the location where <a href="http://en.wikipedia.org/wiki/Star_formation">stars form</a> and start as open clusters.</li>
<li>The distance between stars is usually a few lightyears; in globular clusters it's well below a lightyear. In the galactic center (<a href="http://en.wikipedia.org/wiki/Bulge_%28astronomy%29">bulge</a>) stars are also closer to each other. The diameter of a star can vary from about 10 kilometers (<a href="http://en.wikipedia.org/wiki/Neutron_star">neutron stars</a>) to several astronomical units (<a href="http://en.wikipedia.org/wiki/Red_supergiants">red supergiants</a>), the mass from <a href="http://en.wikipedia.org/wiki/Brown_dwarf">about 13 Jupiter masses for brown dwarfs</a> (or by a stricter definition <a href="http://en.wikipedia.org/wiki/Red_dwarf">from 0.075 solar masses for red dwarfs</a>) to  <a href="http://en.wikipedia.org/wiki/List_of_most_massive_known_stars">several 100 solar masses</a>.</li>
<li>A galaxy center is mostly populated by a <a href="http://en.wikipedia.org/wiki/Supermassive_black_hole">supermassive black hole</a> (SMBH), with about 0.1% the mass of the galaxy, the mass of the SMBH can vary from galaxy to galaxy.</li>
<li>Galaxies can collide and temporarily form <a href="http://en.wikipedia.org/wiki/Irregular_galaxy">irregular galaxies</a>.</li>
<li><a href="http://en.wikipedia.org/wiki/Planetary_system">Planetary systems</a> around stars seem to be common; they are thought to form from <a href="http://en.wikipedia.org/wiki/Protoplanetary_disk">protoplanetary disks</a> shorty after the central star has formed. The outermost part of planetary systems may reach out half a lightyear, to the limits of the <a href="http://en.wikipedia.org/wiki/Hill_sphere">Hill sphere</a> of the central star; it depends on the distance and mass of neighbouring stars. Planets can form outside the <a href="http://en.wikipedia.org/wiki/Roche_limit">Roche limit</a> of a star; small asteroids can survive closer to the central star for some time. A planetary system can contain planets, dwarf planets, moons, asteroids, trojans, comets, dust, magnetic fields, stellar wind.</li>
</ul>

<p>That's certainly still incomplete, and most of the notions can be subdivided to much more detail.</p>

CC BY-SA 3.0
2014-04-03T11:18:34.727Z
Thanks this is a great summary! Though, as I said, this gives me a very vague idea of what the universe looks like, but I still have a hard time visualising it in my head. I'm looking for a more visual explanation. Though it still helps a lot! (Especially all the links explaining terms you use are brilliant!)
The Oddler
CC BY-SA 3.0
2014-04-03T12:18:41.920Z
@TheOddler [This](http://in-the-sky.org/ngc3d.php) map can give you an idea of the Virgo Supercluster. Everything is only mapped by points, but zoom in and out and it's still fairly interesting.
called2voyage
CC BY-SA 3.0
2014-04-03T15:44:23.010Z
@called2voyage thanks! That an awesome map :D
The Oddler
CC BY-SA 3.0
2015-05-02T23:31:59.853Z
How many galaxy clusters and galaxy groups are contained in a typical galaxy supercluster?
set5
CC BY-SA 3.0
2014-04-02T14:19:31.303Z
2014-04-02T21:41:55.217Z
2014-04-02T21:41:55.217Z
Gerald
<p>I've been working on a space game in my spare time, and lately I've been thinking on how to lay out the universe. Though I've searched around and found it hard to get a good view of what the universe looks like. I did find a lot of good sources, though I'm a very visual learner and found it hard to get a good picture of the universe with what I found. I also don't know what the good, reliable, accurate and up-to-date sources were.</p>

<p>So, are there any good visual sources to get a picture of the universe? Preferably a TV-series or a very well illustrated book, or perhaps even computer program.</p>

<p>Edit: I'm looking for a more general view of the universe. Like what do galaxies look like, and what is their scale. As I understand they contain a combination of planets, solar systems, star clusters, ... Though I couldn't get a good picture of how dense they are. Is there a lot of space (relatively) between these solar systems and star-clusters. I found that our solar system is about 4 light-hours big, though are the neighbouring ones average light years or thousands of light-years away? And in the space between them, is it mostly empty or is there space dust?
The same question for whatever our galaxy circles around (if it does) and what is between different galaxies. (And perhaps what else is there of galaxy-size out there?)</p>

<p>I got a vague view of all of this from reading texts, though I feel like I'm missing a whole lot.</p>

<p>Edit 2: I'm not looking for properties of different planets, that's on a too small scale. In the game I'm planning on making a fictional universe (perhaps randomly generated, though not yet decided), but I want the broad layout to be realistic.</p>

<p>Edit 3: I just found this: <a href="http://htwins.net/scale2/" rel="noreferrer">http://htwins.net/scale2/</a> This helped me A LOT in getting a sense of the relative size of things.</p>

<p>Thanks a lot!</p>

CC BY-SA 3.0
2014-04-02T11:20:49.090Z
For clarity, you're asking about the *observable* universe, right? Because we don't even known what's beyond the visible horizon. Also, the observable universe has a 13.7 billion light year observation radius (the actual distance is further due to expansion, see Gerald's answer), so there's a lot of areas that we don't have a lot of detail on. How much detail are you expecting? What do you hope to use the picture for in the space game?
called2voyage
CC BY-SA 3.0
2014-04-02T11:55:15.893Z
Please explain exactly what are you referring to. Shape? Distribution of matter? Size? Connectivity?
Envite
CC BY-SA 3.0
2014-04-02T14:37:40.727Z
@called2voyage, yes I'm talking about the observable universe, since. I'll update the question with more details about what I'm looking for.
The Oddler
CC BY-SA 3.0
2015-01-27T11:40:26.103Z
Make sure that more distant objects look larger than nearer objects, so it gets realistic and [not "naive"](https://astronomy.stackexchange.com/questions/8674/do-objects-look-larger-the-further-away-they-are-beyond-z-1).
LocalFluff
<universe>
Layout of the universe
The Oddler
# Layout of the universe

(Asked by: username_0 on 2014-04-02)

I've been working on a space game in my spare time, and lately I've been thinking on how to lay out the universe. Though I've searched around and found it hard to get a good view of what the universe looks like. I did find a lot of good sources, though I'm a very visual learner and found it hard to get a good picture of the universe with what I found. I also don't know what the good, reliable, accurate and up-to-date sources were.

So, are there any good visual sources to get a picture of the universe? Preferably a TV-series or a very well illustrated book, or perhaps even computer program.

Edit: I'm looking for a more general view of the universe. Like what do galaxies look like, and what is their scale. As I understand they contain a combination of planets, solar systems, star clusters, ... Though I couldn't get a good picture of how dense they are. Is there a lot of space (relatively) between these solar systems and star-clusters. I found that our solar system is about 4 light-hours big, though are the neighbouring ones average light years or thousands of light-years away? And in the space between them, is it mostly empty or is there space dust?
The same question for whatever our galaxy circles around (if it does) and what is between different galaxies. (And perhaps what else is there of galaxy-size out there?)

I got a vague view of all of this from reading texts, though I feel like I'm missing a whole lot.

Edit 2: I'm not looking for properties of different planets, that's on a too small scale. In the game I'm planning on making a fictional universe (perhaps randomly generated, though not yet decided), but I want the broad layout to be realistic.

Edit 3: I just found this: <http://htwins.net/scale2/> This helped me A LOT in getting a sense of the relative size of things.

Thanks a lot!

**Tags:** universe

> **Comments:**
> **username_1**: For clarity, you're asking about the *observable* universe, right? Because we don't even known what's beyond the visible horizon. Also, the observable universe has a 13.7 billion light year observation radius (the actual distance is further due to expansion, see username_4's answer), so there's a lot of areas that we don't have a lot of detail on. How much detail are you expecting? What do you hope to use the picture for in the space game?  
> **username_2**: Please explain exactly what are you referring to. Shape? Distribution of matter? Size? Connectivity?  
> **username_0**: @username_1, yes I'm talking about the observable universe, since. I'll update the question with more details about what I'm looking for.  
> **username_3**: Make sure that more distant objects look larger than nearer objects, so it gets realistic and [not "naive"](https://astronomy.stackexchange.com/questions/8674/do-objects-look-larger-the-further-away-they-are-beyond-z-1).  

---

## 1 answers

### Answer by username_4 on 2014-04-02. Score: 22

[Here](http://upload.wikimedia.org/wikipedia/commons/0/0f/Earth%27s_Location_in_the_Universe_SMALLER_%28JPEG%29.jpg) is an overview of different scales we may look at the universe. On scales beyond it's almost homogeneous, and we get at the border of the visible universe. Many detailed images are available, e.g. from the [Hubble Space Telescope](http://www.nasa.gov/mission_pages/hubble/multimedia/index.html#.UzwUl6h_uqh).

If you need a three-dimensional description of the universe, your program will probably need to read portions of star, cloud, star cluster or galaxy catalogs, similar to a planetarium software.

The general structure of the universe, and its contents may be summarized the following way:

* The [observable universe](http://en.wikipedia.org/wiki/Observable_universe) has a diameter in the order of 10s of billions of lightyears; it depends on which of the several [notions of distance](http://en.wikipedia.org/wiki/Distance_measures_%28cosmology%29) is chosen. For distances below a few hundred million lightyears the notions get similar.
* The universe is about 13.8 billion years old, started as a hot and dense state (Big Bang), expands, and is almost 3-dimensional Euclidean plus one time dimension on large scales; that kind of space plus time is called a [Minkowski space-time](http://en.wikipedia.org/wiki/Minkowski_space). Its average temperature is now near 2.7 K; we can detect a background of this temperature as [cosmic microwave background](http://en.wikipedia.org/wiki/Cosmic_microwave_background) (CMB); the CMB is thought to be the redshifted afterglow of its state as hot plasma at 380,000 years after the Big Bang.
* The universe mainly consists (according to current models) of [dark energy](http://en.wikipedia.org/wiki/Dark_energy) (about 70%); that's invisible; dark energy is thought to be equally distributed, although this is going to be investigated in more detail.
* Most (about 63%) of the matter is cold (slow) and "dark", but not equally distributed. [Dark matter](http://en.wikipedia.org/wiki/Dark_matter) is thought to form large halos around galaxies and galaxy clusters. It's invisible and interacts via gravity with ordinary matter. It can be inferred from [gravitational lensing](http://en.wikipedia.org/wiki/Gravitational_lens) and the velocity distribution of stars within galaxies.
* Much of the remaining matter consists of hot (fast) [neutrinos](http://en.wikipedia.org/wiki/Neutrino); they are very hard to detect, but they can be detected, and they can be inferred from nuclear decay measurements.
* Part of the energy of the universe consists of photons (e.g. radiowaves, light, x-rays, gamma rays, magnetic and electric fields).
* A minor part (about 5%) of the universe consists of atoms and ions (simplified called [baryonic matter](http://en.wikipedia.org/wiki/Baryon#Baryonic_matter)); that's the kind of matter we know from our immediate experience.
* About half of the baryonic matter in the universe is thought to be the [intergalactic medium](http://en.wikipedia.org/wiki/Warm%E2%80%93hot_intergalactic_medium) made of a rarified plasma, consisting of hydrogen atoms, protons, electrons, helium ions. It's thought to form huge filaments around [voids](http://en.wikipedia.org/wiki/Void_%28astronomy%29) of roughly 100 million light years diameter.
* The filaments connect and embed galaxy [superclusters](http://en.wikipedia.org/wiki/Supercluster). Our local galaxy group is part of the [Virgo supercluster](http://en.wikipedia.org/wiki/Virgo_Supercluster).
* Galaxy superclusters are made of [galaxy clusters](http://en.wikipedia.org/wiki/Galaxy_cluster) (diameter up to about 30 million lightyears), like the [Virgo cluster](http://en.wikipedia.org/wiki/Virgo_Cluster), and [galaxy groups](http://en.wikipedia.org/wiki/Galaxy_group) (diameter up to about 10 million lightyears), like the [Local Group](http://en.wikipedia.org/wiki/Local_Group). Sometimes an intermediate grouping (between supercluster and cluster) like a galaxy cloud is defined.
* Galaxy clusters contain up to about 1000 galaxies, galaxy groups less than 50. Galaxies may have sizes about 100,000 lightyears across, and consist (besides a halo of dark matter) mainly of [interstellar gas and dust](http://en.wikipedia.org/wiki/Interstellar_medium). After galaxy collisions this gas may be consumed by star formation or removed from the galaxy. A galaxy typically contains billions of stars. Interstellar gas of different temperature is distinguished.
* Galaxies can contain stars across the [Hertzsprung-Russel diagram](http://en.wikipedia.org/wiki/Hertzsprung%E2%80%93Russell_diagram), neutron stars, black holes, sometimes supernovae, and [rougue planets](http://en.wikipedia.org/wiki/Rogue_planet), probably also smaller rocks ejected from planetary systems. Stars can be grouped to binary, ternary or larger systems of stars up to open and [globular star clusters](http://en.wikipedia.org/wiki/Globular_cluster). Globular clusters are usually old, located in the halo of a galaxy, and contain up to about a million, mostly old stars, may be with a black hole ([IMBH](http://en.wikipedia.org/wiki/Intermediate-mass_black_hole)) in their center. [Open clusters](http://en.wikipedia.org/wiki/Open_cluster) are mostly young and in the [galactic disk](http://en.wikipedia.org/wiki/Disc_%28galaxy%29). A couple of different galaxy types are distinguished, e.g. [elliptical](http://en.wikipedia.org/wiki/Elliptical_galaxy) and [spiral galaxies](http://en.wikipedia.org/wiki/Spiral_galaxy). Dense [molecular clouds](http://en.wikipedia.org/wiki/Molecular_cloud) may be the location where [stars form](http://en.wikipedia.org/wiki/Star_formation) and start as open clusters.
* The distance between stars is usually a few lightyears; in globular clusters it's well below a lightyear. In the galactic center ([bulge](http://en.wikipedia.org/wiki/Bulge_%28astronomy%29)) stars are also closer to each other. The diameter of a star can vary from about 10 kilometers ([neutron stars](http://en.wikipedia.org/wiki/Neutron_star)) to several astronomical units ([red supergiants](http://en.wikipedia.org/wiki/Red_supergiants)), the mass from [about 13 Jupiter masses for brown dwarfs](http://en.wikipedia.org/wiki/Brown_dwarf) (or by a stricter definition [from 0.075 solar masses for red dwarfs](http://en.wikipedia.org/wiki/Red_dwarf)) to [several 100 solar masses](http://en.wikipedia.org/wiki/List_of_most_massive_known_stars).
* A galaxy center is mostly populated by a [supermassive black hole](http://en.wikipedia.org/wiki/Supermassive_black_hole) (SMBH), with about 0.1% the mass of the galaxy, the mass of the SMBH can vary from galaxy to galaxy.
* Galaxies can collide and temporarily form [irregular galaxies](http://en.wikipedia.org/wiki/Irregular_galaxy).
* [Planetary systems](http://en.wikipedia.org/wiki/Planetary_system) around stars seem to be common; they are thought to form from [protoplanetary disks](http://en.wikipedia.org/wiki/Protoplanetary_disk) shorty after the central star has formed. The outermost part of planetary systems may reach out half a lightyear, to the limits of the [Hill sphere](http://en.wikipedia.org/wiki/Hill_sphere) of the central star; it depends on the distance and mass of neighbouring stars. Planets can form outside the [Roche limit](http://en.wikipedia.org/wiki/Roche_limit) of a star; small asteroids can survive closer to the central star for some time. A planetary system can contain planets, dwarf planets, moons, asteroids, trojans, comets, dust, magnetic fields, stellar wind.

That's certainly still incomplete, and most of the notions can be subdivided to much more detail.

> **Comments:**
> **username_0**: Thanks this is a great summary! Though, as I said, this gives me a very vague idea of what the universe looks like, but I still have a hard time visualising it in my head. I'm looking for a more visual explanation. Though it still helps a lot! (Especially all the links explaining terms you use are brilliant!)  
> **username_1**: @username_0 [This](http://in-the-sky.org/ngc3d.php) map can give you an idea of the Virgo Supercluster. Everything is only mapped by points, but zoom in and out and it's still fairly interesting.  
> **username_0**: @username_1 thanks! That an awesome map :D  
> **username_5**: How many galaxy clusters and galaxy groups are contained in a typical galaxy supercluster?  

---

