I suspect it will be in billions of years when the sun goes red giant. If you are referring to some ridiculous Biblical 'prophecy', that is just as ludicrous as this Nibiru crap. The 'return of Jesus; has been forecast so many times - including in the Bible itself when it said that people alive then would not die before the return. Funny how myths and superstitions have a way of turning out not to be true isn't it?