A lot of people reading this probably weren't even born the last time this happened, so it's pretty rare. The last one was in 1982, and if you miss this one while you're watching Fear the Walking Dead or something, you'll have to wait until 2033 to see it again. Set the DVR.
Tonight's event is actually three events coming together, according to Space.com. It's a full moon, plus a lunar eclipse where the Earth blocks the sun's light from the moon, plus lunar perigree (aka super moon) when the moon is closest to Earth, making it look much bigger and brighter.
Of course, whenever something like this happens, people start saying it's the end of the world. According to CNN, some Christian ministers calling this a "blood moon" say the event fulfills a biblical prophecy predicting the apocalypse, because it's the fourth in a series of blood moons. But I guess it depends who you believe, because the Mormon church released its own statement telling everyone to chill.
The Earth's shadow will start making its way across the moon at 8:11 p.m. ET, and the eclipse will peak at 10:47 p.m.