Hi all, just wanted to have some explanation to this topic. LOL. Btw, I'm talking about how MCU lays out these worlds on their movies.

As we know, the 9 realms are namely:
1. Muspelheim
2. Alfheim
3. Vanaheim
4. Asgard
5. Midgard
6. Jotunheim
7. Nilfheim
8. Svartalfheim
9. Helheim

- in which Midgard is Earth. As we have seen in Thor 2, due to the Convergence where the realms' portals became accessible, Thor and Malekith are able to randomly go to these realms as they fight causing the Mjolnir to fly up to space as Thor accidentally goes into a realm (not sure if it's Svartalfheim) then flies back to Earth as soon as Thor gets back to England.

The thing here is, if Midgard = Earth, then are the other realms planets as well? Then why are there only 9? From the example above, we've seen Mjolnir fly up through space. Does this mean that these realms are accessible through space travel? How are these realms situated in space?

Sorry for the questions, just wanting to find an answer/theory on this. Thanks!

Pretty sure they all care more about the animation than the logic.
If you really want the details, I suggest you look at the Yggdrasil Diagram from Norse mythology