ummmm...
it says "still scene"... why not something animated? see... this sort of scene just begs for someone to use GIMP, or PhotoShop... not anim8or, to produce something.... doesn't it?
The advantage of this topic is that it's as difficult as you make it.
If you decide to model the Earth and the Moon, than you'll definitely spend most of the time working on the textures in Photoshop/Gimp, because all you need to do in Anim8or is to create the 2 spheres... However, if you decide to create a fully detailed model of the International Space Station, then I believe you'll use Anim8or more than enough! It's just what you make it
does the scene have to be in outer space? or can it be from inside a ship?
How much of the image has to be "Space"?
And what constitutes "Space"?
Just do whatever you want! If the scene is inside a ship, it should be obvious that the ship is somewhere in the space (a space ship that is standing on the runway definitely doesn't count for a space scene!).
Ok, now what does it mean "to be somewhere in the space"?
Here is a nice Wikipedia definition:
Outer space (often simply called space) comprises the relatively empty regions of the universe outside the atmospheres of celestial bodies. Outer space is used to distinguish it from airspace and terrestrial locations.
That's it. Just try to focus on those "relatively empty regions of the universe"