How rare is the event? Even without the supermoon, it's the first blue moon total lunar eclipse in the U.S. since March 1866, less than a year after the Civil War ended, according to EarthSky.org.
A blue moon — which occurs about every 2½ years — is another term for the second full moon in a single calendar month. January's first full moon occurred Jan. 1.
Though the exact moment of this full moon is 8:37 a.m. ET Jan. 31, the moon will appear plenty full for a day or two before and after that.
However, the moon doesn't actually appear blue.