A Secret Land

Zei: This room is a true marvel, a mechanical wonder. It's a planetarium that shows the heavens moving. Sokka: Uh, this is beautiful, but how is it helpful? Katara: Maybe these dials represent dates and times. Sokka, try entering that date from that parchment you took. [...] Hey, wait. What happened to the sun? A: Great, you must have broken it. S: It's not broken. The sun is behind the moon. It's a solar eclipse! It's literally the darkest day in Fire Nation history. Now I get it. Something awful happened on that day. I don't know what, but I do know why. Firebenders lose their bending during a solar eclipse. [...] K: That makes sense. I mean, think what the lunar eclipse at the North Pole did to the waterbenders. This is huge.