Originally by: Kimochi Rendar
However, I imagine that really big ships like the Leviathan titan hovering over Caldari Prime, or big fleets of ships would probably be visible from the surface, especially if they where close. The battles above Caldari Prime and during the Minmatar invasion would have been quite spectacular I think!
From the ground, even that titan would cover maybe a few square millimeters of sky at most.
The thing to remember about seeing things in space is that mostly you don't see the object itself - just the light reflecting off it. some objects with a high reflective index (Albedo) can be more visible than their much larger neighbours by dint of having a higher albedo.
The reason Venus is so visible in the night sky is because its atmosphere gives it an incredibly high albedo. Same goes for Jupiter, the ISS and comets.
Consider this - an airliner at 30,000 feet is visible with the naked eye, but it's actually vanishingly small - you can easily cover it with a paperclip or pin. The moon, despite being a full 1/6th the size of the Earth, can be obscured by your little fingernail at arm's length. The single largest visible object in the sky - the constellation Hydra - can be hidden behind your outstretched palm.
The point here is, things get very, very small indeed as they get further away from you. at 10,000 Km, I reckon the only things you'd stand a hope in hell of seeing unaided would be supercapitals, and even then they'd be little more than faint grey smudges in the in the night sky, maybe with a swarm of little lights around them.
Amarr ships would be the most visible (those shiny, round golden hulls would have a very high albedo), followed by caldari ones (mostly grey, plenty of running lights), Gallente (dull grey/green ceramic composites don't reflect much light...) then Minmatar. Missile explosions - especially torpedos - would be very visible.
All of this would still be happening at luminosities massively smaller than the backscatter of city lights off the planet's upper atmosphere, though. You'd need to be waaaay out in the sticks, so that the whole horizon in any direction is utterly clear of light pollution before you'd have a reasonable chance of seeing these ships.
I still say that a warping ship would appear as a fleeting blue line across the sky, though. near busy spacelanes, the sigh of all those ships warping past would be a lot like watching a meteor shower.