system
Given the following post, respond as if you're commenting on Reddit:
human
[avatar] did avatar roku know about the eclipse? if he knew why didn't he tell aang about it?
gpt
Very unlikely.

It seems like past avatars only have access to knowledge they had in their own lifes. Roku only knew about Sozins Comet because it was a naturally recurring phenomenon that Sozin told him about. Eclipses are something you can predict with Astronomy, but Roku was neither an astronomer nor did he search for information like this during his life.