The moon blocks the sun.
A solar eclipse occurs when the moon, specifically a new moon, passes between the Earth and the sun, blocking sunlight from getting to Earth. A total solar eclipse is very rare. But this was their chance, for firebenders lose their bending during solar eclipses.
There is a catch. The solar eclipse only lasts for a few minutes, and can only be viewed from a very small portion of Earth. They could do it though; this was their only chance.
The moon blocks the sun.
It was coming. He could feel it in his blood. The others were oblivious to it, but he knew, and he was prepared. His twin swords were sharpened and hidden away, yet within easy reach. There would be no time to attack the Water Tribe during the lunar eclipse if the Avatar defeated them first.
He didn't know whether to warn them or not. It was coming.
The moon blocks the sun.
The siege began, and she did not stop. Even when she was separated from Aang and Toph, she kept going. Even when she was lost, she did not stop. Even when she saw him coming, she did not stop.
The moon blocks the sun.
He must keep moving. He had left without a word of warning, and needed to be gone before they realized. Azula would have his head. But then she stepped in the way and shouted. When that didn't work she pleaded. And he answered.
The moon blocked the sun.