That's when the Crystal cracked. That's when the Skeksis appeared. And the Mystics.
8 seconds sound clip from the The Dark Crystal (1982) movie soundboard.
You can hear this line at 00:26:22 in the Blu-ray version of the movie.
Quote context
[...]
- Is that it, Gelfling? You don't know?
- You've never looked at the heavens. Everything in the heavens is here moving as the heavens move.
- This is how to know when. That's what. Suns, moons, stars.
- Yes, the angle of eternity. That's how I know it's coming. How else can I make the prediction?
- A thousand years ago, there was a Great Conjunction. I was there. Three suns lined up.
- That's when the Crystal cracked. That's when the Skeksis appeared. And the Mystics.
- Better have your Shard before that, Gelfling.
- Now, ask what the Great Conjunction is. What's the Great Conjunction?
- What's the Great Conjunction? You tell me.
- The Great Conjunction is the end of the world or the beginning. End, begin. All the same.
[...]