Dresden Files IN SPACE!

[darth_borehd]

Is it possible to use the NeverNever to visit other planets?  Could Harry find a shortcut to Mars and explore it using a magical spacesuit? 

[Griffyn612]

There is a WoJ that to reach the Gatekeeper's domain, you have to walk across the surface of the moon.  So I'd say it's possible.

[Quantus]

The first WOJ is answering your specific question, the other two offer some additional related info. 

2011 Bitten by Books Q&A
My question “Could you use the NeverNever to travel to other planets like Mars for example?”
You can’t get much farther out than the moon, in terms of moving through normal space–and it’s /hard/ to get that far.

Iago says that at the 2010 DragonCon, Jim told him:
"You get to the Gatekeeper's domain by walking across the surface of the moon."

2012 Reddit AMA:
Dudesan: What we've seen of the cosmology of The Dresden Files seems very Earth-centric. Is that because everything really does revolve around the Earth[1] , or because we're seeing only a tiny slice of a much bigger picture? Are there other planets in real-space inhabited by extraterrestrial sentient beings? If so, do they have their own analogues of wizards, fairies, gods, etc? Are supernatural things influenced by their belief as it is by those of humans? If so, to what extent do these "spheres of influence" overlap?

Jim: 3) Everything revolves around /this/ earth, in the Dresden stories. But not necessarily around all (or even a majority of) the other earths that exist in the continuum of possibility created by free will. Other, parallel realities have other worlds playing a more central role, and some of them have earth in a nice quiet backwater, peaceful, relatively conflict free, and boring.

[ethical crackpot]

Is the reason you can only get to the moon through the never never because that is as far as people have gone? It would make sense given that the beings in the never never need to be thought of by people to have a connection to this world.

[Tami Seven]

Is the reason you can only get to the moon through the never never because that is as far as people have gone? It would make sense given that the beings in the never never need to be thought of by people to have a connection to this world.

That sounds like a good theory to me.

[Rasins]

So, with the cults of extraterrestrials that are in existence now, do you think links to other planets, even if they are fictional, could start to be being formed?

Jim has said that through the never-never, one COULD reach the Jedi Galaxy.

[Orion Ultor]

So, with the cults of extraterrestrials that are in existence now, do you think links to other planets, even if they are fictional, could start to be being formed?

Jim has said that through the never-never, one COULD reach the Jedi Galaxy.

But are they the real thing (parallel or alternate universe) or just a reflection/demesne within the NeverNever?

[Rasins]

But are they the real thing (parallel or alternate universe) or just a reflection/demesne within the NeverNever?

Great question.  I think we'd have to hear from Jim on it.

[Quantus]

So, with the cults of extraterrestrials that are in existence now, do you think links to other planets, even if they are fictional, could start to be being formed?

I doubt it, considering that you cannot reach further than the Moon via NN Ways, even though Science has actually reached Mars. 

Jim has said that through the never-never, one COULD reach the Jedi Galaxy.

He just said it was reachable within the Multiverse.  Whether you can reach Alternate realities through Ways travel has not bees confirmed (or even addressed, iirc), but I strongly suspect the answer is No because NN denizens are still equally bound by the splits of the Multiverse (there will be multiple Mabs, etc).