Finally got around to reading Dune

Earth is described as “gone” by Darwi Odrade in Chapterhouse, but the Dune Encyclopedia describes it as once depopulated (possibly asteroid stike) and then re-populated and the ultimate source of the Zensunni.

The plot significance is that worms can be transplanted to other planets, I guess.

They’re guiding them, but they have FTL engines (Holtzman drive). They’re not just plotting a course ahead of time, they’re actively steering the ship (Steersman is an alternate title for a Navigator).

I think the point of bringing that up is to start cluing the reader in to the fact that the worms are the cause of Arrakis’ climate.