Well, there are 2 big ones in the bible that we know of.
But for sure they seem to be happening more.
Part of signs in the sky for the last days
Nicole Poon from Hong Kong has made many such prophetic
sketches during prayer
Here is one of them
18th May 2013/Today we studied about Jacob's
prophecy to his descendants.God's prophecy to Israel
until today we are still waiting.I still prayed for
almost the same.In my prayer my friend saw a unknown
purple object with purple light hitting the sea very
fast in a starry night in 1-2 second.