The resignation of Pope Benedict XVI came like "a bolt from the blue", according to the dean of the College of Cardinals, Angelo Sodano.
And it wasn't just the Vatican and Catholic followers who were shocked.
Lightning strikes St Peter's dome at the Vatican
Just hours after Pope Benedict XVII announced his resignation, a bolt of lightning came down from the heavens, hitting the dome of St Peter's Basilica.
The Renaissance church is one of the holiest Christian sites.
The Pope announced his intention to resign on February 28, which is when the selection process for a successor will begin, in the hope of appointing a new pontiff by Easter.
The Vatican said immediately after his resignation that Pope Benedict will go to Castel Gandolfo, a summer retreat south of Rome, and then would live in a cloistered monastery.