The moon is providing a rare triple treat this week. On Wednesday, much of the world will get to see not only a blue moon and a “supermoon,” but also a total lunar eclipse. Having all three events taking place at the same time is extremely unusual. Astronomers say this has not happened since 1982. And it won’t happen again until 2037. A total lunar eclipse happens when the Earth comes between the Sun and a full moon. The Earth blocks the sun’s light, making the moon appear dark in the sky. The eclipse will be easiest to see in the western half of the United States and Canada before the moon sets early Wednesday morning. It will also be visible across the Pacific Ocean into East Asia as the moon rises Wednesday night into Thursday.