My peach-apple oxidized a bit as I was juicing and started fermentation amber-brown. Over two days of rapid fermentation with Safale US-O5 dry ale yeast, the color lightened to a pale yellow, straw color. Anyone know anything about this?
That's the color of yeast in suspension. When the yeast flocculate the color will go away and the cider should be clear. Also remember that when you're looking at a fermenter, you're looking through a lot more beer than you would see in a glass, so color and haze will appear more intense. The name of this phenomenon is easy to remember: Beer's Law.
When the yeast flocculate and the cider is clear, it will probably be ready to serve or bottle. Of course, check the gravity & taste to be sure there isn't too much sugar remaining.