Dozens of remote control helicopters programmed to fly in
various patterns that trail below them a long string of very
bright flares of various colors. These flares are ignited at
pre-determined times when the helicopter is at the correct
position and time for the particular animation pixel to
be
shown.
Some animations might include:
A dolphin made of "stars" swimming across the sky.
A standard fireworks explosion but in slow motion.
A mile wide spiral that would make the whole audience feel
like the world is spinning.
Flying to the various constellations and highlighting them.
Multiple "stars" flying at the audience giving the effect that
they're accelerating through space, a-la when they enter
warp speed in science fiction. (Star Wars, Star Trek, etc)
Of course just flying into particular shapes and flying apart
into different shapes, perhaps with a narration over the
loud speakers telling a story.