My guess is that the realms just refer to different galaxies in MCU, whereas most of the aliens like the chitauri or kree are from the Milky Way (aka, Midgard).
According to Wikipedia, the Kree are from the Large Magellanic Cloud.
In the comics.
Why can't the Local Group be "Midgard"...or the Virgo Supercluster for that matter. Thor said we've only glimpsed part of Yggdrasil through Hubble, so maybe most of it is beyond out observable universe.
*Note for those not up on astrophysics: that doesn't mean it's in an alternate universe. The "observable universe" is just the objects who's light has had enough time since the big bang to reach us. There's a lot more out there that we can't see because the light is still route...of course by the time that light gets here, those objects would be long gone...but then so will we, but I digress.
Really though I'm thinking the Nine Realms are just terminus points of a cosmos spanning network of wormholes, with Midgard (Earth/Sol, specifically) being at the central crossroads. With that in mind, there's going to be vast expanses of space in-between, from whence the likes of the Kree, Shi'ar, Skrulls etc. are to be found. And I mean *VAST*.
Clearly this network is not the only way of getting around (see: the tesseract), but I'd wager it's probably the widest ranging and fastest way to hop from one side on the universe to another. This is probably the real source of Asgard's power since that realm appears to be in a dominant position, better connected than the others but not as vulnerable on all sides as Earth is down at the centre.
I don't disagree, but you'd think Heimdall would have noticed at least. I mean that's his job, no? Those Kree must have been *very* sneaky.
He may have. But his duty is to protect Asgard, not Midgard.
Then why did Asgard protect Earth from the Frost Giants?
That's besides the point though. The point I was making was that if he saw it, Odin would have been made aware and so too would the likes of Thor, Loki, Sif, etc. Plus the way Sif said it, implies that Asgard has been keeping watch.
It's not
"Rest easy, Phillip, son of Coul. I don't actually know for a fact but I'm sure if Heimdall saw any blue aliens here, he'd probably do nothing, except maybe leave Odin a note."
It's
"Rest easy, Phillip, son of Coul. None of the others have ever visited Earth." She's stating it as a fact, as if she has good reason to make this assurance.
Yeah, she's wrong and that's what has me wondering. Can the Kree, or whichever race that nicked off with Star Lord really move about under Heimdall's nose? To date we've only seen other Asgardian's pull this off. The Dark Elves were able to get very close, but he was able to detect them. Loki could sneek right past him without him even knowing.
And the difference between "dimension" and "universe" differs depending on which franchise/work you're talking about. But then there's Star Trek. Would you call a subspace fold or whatever from Star Trek an alternate dimension or an alternate universe? Cause then there's parallel quantum realities like the mirror universe and the Abramsverse.
Like I said though, it's a mis-used term that doesn't actually mean anything. "Alternate dimension" implies that we exist in one, when in fact we exist in at least three simultaneously (possibly more, but let's try and keep this simple.)
Basically put, Asgardians, Frost Giants, Dark Elves, the other inhabitants of the Nine Realms we've seen and the worlds from which they come are all within the same three dimensional Euclidean space as we are. If they're from an "alternate" anything, it's alternate universes that are very similar to our own. But that's not how things have been presented. Indeed they've been pretty consistent in that Yggdrasil is a physical thing and the Nine Realms are all operating within the same space-time continuum.
Also, I really wouldn't use Trek are a basis for these frames of reference. Indeed it's one of the worst offenders for misusing or inconsistently using scientific terminology, to say nothing of the gibberish they flat-out made up. You may as well cite the demon dimensions from 'Buffy the Vampire Slayer' for all it's scientific accuracy.
