posted on Dec, 3 2009 @ 09:38 AM
When you say "large flash", do you mean you saw the source of the flash, or do you mean the sky lit up, but there was no obvious source?
It may well have been a meteor, although sometimes, when a electricity substation transformer blows, it can light up the sky and may be visible many
tens of miles away.
If you did see a meteor, it's unlikely that it would have been iron as the previous poster said. Greens and blues can be created by any meteor, and
if it was iron, it would probably have been quite a long-lived event, since iron is quite hard (at least compared to asteroidal and cometary