The blood moon is the total lunar eclipse. During the total lunar eclipse, moon becomes reddish. We called the blood moon. The blood moon tetrad is four blood moon during the Passover and the feast of Tabernacle. It has been 8 times of the blood moon tetrad for the last 2000 years. In this year and next year, there have 4 blood moons during the Passover and the feast of Tabernacle. The next blood moon is 568 years later.
I believe that this year and next year blood moons tetra is the sixth seal blood moon in the chapter 6 of the book of revelation. That means, it will bring the great earthquake and asteroid on the earth. Not only the blood moon but also Shemitah is coming this year and next year. The day of His coming is soon! Be ready for the coming Messiah!