Why do time and distance seem to disappear in the Planetariun?

Planetarium is a magical place, where time and distance seem to disappear. But why is that happening?

I think that it is because of our perception of reality. It is always hard to navigate when you don't see the ground under your legs. But in there the problem is even bigger - you can't even see your legs! It can be kind of confusing for a lot of people not to feel your body by seeing it.

And we aren't really good at inner counting, so without a clock it's pretty hard to track the time.