The Cosmology of Doctor Who
So we know that Doctor Who’s cosmology is different from ours. There, the Moon was (according to 1970s theory) an adopted planetoid… which was, in fact, an egg.
Bizarre thing is, Kill the Moon actually fits classic Who’s jump-the-gun science, that Chibnall said “duh” and perpetuated 40 years later. More than fits it; it makes sense of it.
In the Who timeline, where I guess Earth formed around a (coincidentally egg-laden) Racnoss ship, Gaia (early pre-Earth) must never have collided with Theia (another rocky planet in our orbit, that shattered on collision), as seems to have happened in our world.
What this seems to imply, then, is that in the Who timeline Theia must have remained in Gaia’s solar orbit, somewhere far enough back that the two never collided.
Why didn’t they collide? Possibly that Racnoss ship; it may have altered the early accretion of proto-planetary debris just enough to butterfly (er, spider?) effect away a different spacing and possibly greater mass for the two proto-planets.
Which is to say, the fuckery in Kill the Moon just happens to be consistent with the Silurian recounting of events (as RTD’s weird whimsy), which in turn makes Mondas plausible.
Thanks to Peter Harness, somehow a mountain of awful and/or outdated science balances out to plausible consistency.
All praise the Egg.