The sun going backwards is such a significant event that it's recorded twice in scripture in 2 Kings 20 and Isaiah 38:8. It's also referred to in 2 Chronicles 32:31 as "the wonder that was done in the land".
The Sun Went Backwards
September 23rd
Jerusalem was besieged by the Assyrian army and King Hezekiah was sick and nearly died. Then the sun went backwards. The Assyrian army was wiped out and Hezekiah became internationally famous.