Random Fireworks

Does anyone know why the harbour has just exploded? I love random fireworks. We had just finished work and were sitting in the office checking emails and stuff when suddenly it sounded like the pier was being bombarded. Racing outside we found the sky ablaze, which lasted for the next half an hour.

Sydney loves a good fireworks display and, besides New Years, this was pretty special. We just don't know what for? It would have been nice to have had some warning so I could have brought decent equipment to work to take pictures.