planet sizes??

They can be above 20, too. I've never seen a planet that was naturally above 18, but after Soil Enhancement, Improved Habitats, and Terraforming a planet can certainly be well above 20. I think the best I got a planet was 24.

It is mentioned in the manual, page 28.

There are 26 classes of planets, and 16 and up are incredibly rare. The highest I have seen is 19, but I haven't played as much as most do.

Ah I have had two games where i found and colonized planets above 20, think one of the highest i found is 26 or so. Current game do belive have 2 above 20 one was natural other was 18 and then got a increase pq event have the first level of the race attribute to increase planet quaility

ah well me being daft then. it's just that in my current game, which due to the incredible ability of the AI, even on normal, to churn out fast colony ships as if they were made of paper mache and cost as much, has left me smack in the middle of big empires with 8 planets to my name on a huge map. though 2 very clode to each other are 26. seems i've been very lucky.

and for some reason had it in my head 20 was the top so thought it may have been a lucky bug.

In my current I came across a couple of class 26 planets. Yummy