Board Thread:Questions and Answers/@comment-68.38.63.82-20140802181548/@comment-4051347-20160420175450

The 9 realms are explaned by Thor as 9 different dimentions, It's like Asgard is here on Earth but in another dimention, and this dimention we know as Earth is located is called Midgard, so Midgard is the dimention where Earth (in the Milky Way), Xandar and Knowhere (in Andromeda Galaxy) are all located.