le Pingouin is on the money. It's all about the composition. Small fast meteors (aka shooting stars) generally appear single colour. The most common flash is white - probably for a couple of reasons including the fact that they appear and disappear so quickly, and they are usually not in the centre of the eye where your colour vision is the most sensitive.
For more persistent meteors colours are commonly reported, but generally a uniform colour, depending on the concentration of the predominant metal. Nickel gives off a green tinge - there was a large green meteor crossing the northern sky in Melbourne about 6 years ago that got a similar amount of media attention.
The speed of the meteor might also influence its colour hue, as a slower meteor might not vapourise the metals simultaneously (or at all).
I've seen random falling space junk before - once even in daylight. The multi coloured sparks trailing off it (rather than a vapourised tail) were quite spectacular, but a more homogenous metal structure would not be as colourful.
There are also many reports of an instantaneous sound being emitted from large meteors. Not the delayed sonic booms as the news footage from the Russian one last year showed, but an actual sound being heard whilst watching it - usually likened to a frying pan sizzle. Nothing's proven, but clearly can't be sound waves due to the distance and light/sound speed difference, so the likely candidates are a type of VLF radio wave (travels at the speed of light) that's interacting with the inner ear somehow. I've never heard it though (but don't doubt some can).
As an unrelated tidbit, Chris Hadfield (the Canadian musician/astronaut of Bowie remake fame) mentioned in his book that as you drift off to sleep in space, sometimes you see little flashes of light faintly with your eyes closed. These are solar radiation particles hitting your optic nerve and triggering a sight sensation in the brain. We terrestrial dwellers don't see them as we live under more of the magnetic field that protects us.
For those in the flight deck on red eyes - you are more likely to see a meteor in the pre dawn night sky, as that's the leading edge of the earth and more likely to run into objects. For a meteor to happen at dusk, it's got to catch up to the earth (or be sucked into a decaying orbit). On those Perth Sydney red eyes, dim the cockpit lights, lean over the glareshield and stare outside. Magic.
Last edited by compressor stall; 12th Jul 2014 at 13:13.