Acts, in the New Testament, during which Peter stands up and addresses the crowd with the words of the prophet Joel, referring to the last days:
"I will show wonders in the heavens above and signs on the earth below, blood and fire and billows of smoke. The sun will be turned to darkness and the moon to blood before the coming of the great and glorious day of the Lord. And everyone who calls on the name of the Lord will be saved." (Acts 2: 19-21)
For Buffo to see the moon turned to blood reinforces the idea that his Day of Judgement has come and further extends the links to Christ.