Total lunar eclipse 2018 – much has been written about day after day. And you have been dreaming of the magical night to dawn. Just few more hours and the world will witness the blue moon turn hauntingly blood red on July 27. The longest total lunar eclipse in 21st century will last for three hours and 55 minutes, experts say. And the period when the moon will be completely darkened by the earth’s shadow will last one hour and 43 minutes.