According to the theory (or my understanding of it), the universe is not only expanding, but speeding up. If the galaxies are moving apart, are the solar systems within them also moving apart from ...
So far I got to understand the expansion of space is not to be understood as stars drifting further apart through space. There's something more fundamental - e.g. you can't simply measure speed of it, ...
I'm envisioning an analogy of the universe as a plane with marbles in that plane to represent different planets. Now, if this plane expands how does this work? I assume that it is not like 'nothing' ...