Dragons on the moon?

[Luthien_ Tinuviel]

This topic arises from a brief discussion I had a while ago with one of my LOTR-obssessed friends. Whether or not you take it seriously depends on whether you believe that Roverandom is linked to Middle-earth. It seems to me almost as if Roverandom is meant to be set in a later version of Middle-earth (as indeed is our world):

...imaginatively this 'history' is supposed to have taken place in a period of the actual Old World of this planet.

So, seeing as Roverandom is presumably set in our world, it may very well be assumed that in Roverandom we are dealing with a later version of Middle-earth itself.

With that established, we see that there are dragons on the moon in Roverandom:

All white dragons originally come from the moon, as you probably know...

The moon-dog did not know everything about the moon, as you see, or he would have known that this was the lair of the Great White Dragon...

So how did dragons get to the moon? We know that

[Morgoth] assailed Tilion, sending spirits of shadow against him

But dragons were not spirits, were they? And to get to the moon, dragons would have to pass through Ilmen, a place where "flesh unaided cannot endure".

So how did dragons get to the moon? Any ideas? Or is Roverandom not meant to be taken seriously?

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1. Letters, #165, page 220
2. Roverandom, page 32
3. same as above
4. The Silmarillion, page 117
5. The Silmarillion, page 349