"Space, the final frontier! To boldly go where no one has gone before: The Vue Material Editor!"
Hehe ;) Here's how to make your own starfields in Vue (or other apps), and more advanced nebulas than the ones shown in my previous tutorial :)

  1) STARFIELDS - IMPORTING SPACE PICTURES

  Vue comes with the ability to have it's own stars, just by going into the Atmosphere editor, Effects tab: very simple! However...it's often very lacking. Unlike in most Vue tabs, you cannot put the amount over 100%, nor adjust colour individually etc. Also, it doesn't have any nebulae or galaxies or other odd features of space.

  You can easily load in superb images for spaces backgrounds from the Hubble News Center and other NASA sites , I have a few of my own space backgrounds created in Paint Shop Pro, on my own site, here. Please note that if you do so:
a) Respect copyright laws! I am *no lawyer* so take this with a pinch of salt (all caveats apply): as far as I know, Hubble site images can be freely used in personal *non-commercial* artwork *provided the image is a NASA image and in the public domain*. Check here for Hubble site's copyright notice.
So, if you're making money from an image, *check throughly on any rights beforehand, personally, with who ever made the image*, that's something you should always do anyway.
b) You'll need to do some jiggery-pokery in the material editor to get an imported space pic to look right!

  You can make your own starfields in 2D apps like Photoshop, it takes time and effort though, this is my favourite tutorial on how to do this:
Greg Martin's Starfield Tutorial he also has a .pdf on his site "Capturing Heaven" which is superb, alas his site uses Flash so I can't give you the link, go hunt for it yourself! ;) http://gallery.artofgregmartin.com/

  Ok, to add a Starfield Image in Vue, load up an Alpha Plane and make it a billboard (if your version allows you to do so, otherwise, just a Plane will do). "Billboard" setting means it will always face your camera, which is a Good Thing! (tm) ;)
  The image will be very flat and dull, not like real space at all, so open the Material Editor. First off, make sure the material is set to Object Parametric, so it's not distorted in proportion. Turn off Send and Recieve Shadows, starfields do not to do either as they are vastly too far away.
  Next, you need to turn off all highlights, set them to zero, again, you're simulating vastly distant stars, not a flat plane object, highlights will mess it up.
Go into the Effects tab, turn the Luminosity way up, tweak to taste, from 20% to 100% as need.

  Important note! if the image you have is not good, in that the "black of space" is not truly black, it will gently light up and look fake, so watch for that (you can fix that using "Levels" in Photoshop or other 2d Apps, forcing black to be actually black, rather than very dark grey)

  You can make your own starfield material in Vue, and apply it to a sphere that surrounds the scene, or to a an Alpha Plane, set as Billboard to fill the screen. A sphere allows for animation, as you can move around and it will still be visible, but the sphere need to be HUGE, or the viewer will see stars move, which is obviously fake (a few, close stars may move when a space ship is at high speed, but not far ones). Note also that the "hyperspace" effect of stars warping by you is something else entirely, see Phillipe Bouyer's animation and scene in the Cornucopia3D store for how to do "hyperspace".

  To make the starfield material: Again, turn of Cast & Recieve Shadows, and highlights. Now, for spheres, make mapping Object - Spherical, for Planes make it Object-Parametric.

  Set the colour to white for the moment, and load up the Atmosphere "Black, no stars" so you can test your work (make sure fog/haze are turned off), hide the ground plane from render or delete it.

  Back into the material editor, set Luminous to 100% for now (you can lower later if need or drive with random fractal for variation). Enter function Editor.
  To make the dots for stars, select "Simple Fractal, Other Patterns/Dots", and connect that to the Transparency tab, basically you want to punch lots of tiny dots in this otherwise totally transparent material. Now here comes the tweaking part! You will need to adjust scales to suit your object...that is entirely up to you to find out, but you can take hints from the pics below :)

  There won't be very many stars, as it's only ONE lot of dots! Not enough, so, make another Fractal Dots, then use a Combiner node to join them up. Set Combiner to SUBTRACT, , then do this yet again, so you should have four fractals, each combined into two Combiners (Subtract), then those joined into a final Combiner (Subtract). Plug that into Transparency, but add a filter, you'll need this to"cut out" excess noise, that will ruin the transparency. See the image for details.

  *BUT* and this is a big but, lol, the stars are all the same size and position, so will stack over the top of each and won't be seen! You need to adjust EACH Fractal Dot's Wavelength and origin, slightly: Wavelength = size, Origin = Position.

  Also, stars come in varied colours, from dull reddish through organ to yellow, to pale blue to white (also green to greenish-white as well, rarely, those are massive stars). Star colour depends on type and size: red giants (swollen, massive old stars of titanic size), more normal stars like our Sun (white-orange-yellow), to very young enormous white stars that live and die short and violent. You also have red and white dwarf stars, plus neutron and other exotic types we don't need to bother about ;) You cna og read up about stars on the Web :)

  So, in Vue, make a colour gradient of choice, I used 4 colours: reddish, yellow, white, blue. Then drove that with a Fast perlin Fractal, as shown on the image below, to mix the color up. Note how I put the colours, as adjusting this is trial and error...many, many errors...lol.

  Ok! The actual plural for "nebula" is "nebulae", but not everyone actually uses correct English ;)
Nebulae are enormous clouds of gas and dust, the most obvious form is that of the beautiful glowing plasma clouds, as seen in that image above, from NASA. Sometimes, they are also just dark patches of dust that block light,and form shapes like the famous "Horsehead Nebula", shown below.
  Nebulae are generally created from three things:

• Stars heating up clouds of material until they glow, forming planetary discs, or much larger regions forming Solar systems, those ones can be absolutely enormous, covering thousands of light years across. Sometimes, especially bright clusters of massive, hot young stars show up in such regions, forming beautiful swathes of bright gems in the cosmos, as shown in this previous NASA pic.
• Massive explosions (super novae) blowing a star's material all over the cosmos, the expanding shockwave and energy heats up any dust it hits and the explosion material itself slowly cools, sprinkling space with carbon, iron and heavier elements.
• Patches of dark, cold dust and gas.

  Important point to note, is that the dark patches will seem to "cut out" large chunks of stars and galaxies, because the dark nebula is in the way, but, other stars may be in front of that cloud of debris, so it may have stars showing, or there maybe extremely powerful stars behind or in the cloud still shining through.. It has to be understood that space is not a simple flat plane, but a massively deep sphere surrounding us, so many items are layered up in front of our eyes, just like a Photoshop image.

  The colours in nebulae are caused by gasses bombarded by extreme heat and radition and thus turned into plasma, the fourth state of matter, and it is incredibly hot. It can glow in many colours, although some astronomical images are given "false colour" to show things up better or just to look good, nebula do come in a wide variety of colours. They also get compressed by shockwaves, leaving edges or regions of bright narrow ribbons, check the Horsehead nebula pic below to see this.

  Making a nebula with a Vue material, requires using a fractal to drive transparency, as you only want the nebula to cover a percentage of the object, and another fractal to drive a colour map of your choice (and remember some nebula have black areas or are totally black). Many, many ways to do that, I show one below.

  You can apply the nebula material to a plane, or to a terrain. Procedural terrains can help create some really intricate features due to varying height affecting the nebula. You can also rotate nebula so they are at an angle to camera, again, producing interesting looks. Remember that nebula and space objects can have many layers, so you could have 5 layers of different nebulae, with 2 layers of stars in between, or in front of them.