According to fringe beliefs, it happened on August 16, 1987 and was supposed to be the pre-ordained moment when the 'vibrations' of the Earth were to be synchronized...or something. To an astronomer, it was a moment lacking in any physical significance whatever. It seems a lot of impressionable people spent time standing on mountains or other 'cosmic' spots to feel these etheral vibrations. I am sure if you do a search on AltaVista, under 'harmonic convergence' you will turn up lots of very peculiar documents!