Jesus told us that there would be signs in the heavens as we approach the time of His second coming (Luke 21:11, Genesis 1:14).  This discussion between Scott Clarke and Derek Gilbert on the astronomical sign in Revelation 12 is very interesting.

Scott has more videos on the subject on his Youtube page here.
Derek Gilbert Youtube page here.

Of course I don’t necessarily agree with everything someone teaches, and I always recommend taking everything with a grain of salt.  Be like a Berean and search the scriptures (Acts 17:11).