The key to a successful prophecy is writing it vague enough so that you claim it happened or didn’t happen when you look back in hindsight. Obscure writing happens best when you make it a poem or a quatrain.
I predict on or around July 20th next year a very rare and spectacular astronomical event will occur. That is because on the 25th anniversary of the moon landing a comet smashed into Jupiter and the next July 20th is the 50th anniversary.
Footprints upon another world...
From the heavens a string of pearls!
Five square years they smash Zeus eye.
Five square more another heavenly sign!