It's my headcanon that there's not a galactic-wide holonet. That infrastructure just isn't there. Individual planets like coruscant probably have a holonet, sure, and some core worlds are connected to each other, but for a lot of the galaxy, most of the galaxy even, the average person just doesn't have access to a galactic equivalent of Earth's internet.
So we all know that Tumblr is US-centric. But to what degree? (and can we skew the results of this poll by posting it at a time where they should be asleep?)
In this sonification of Perseus. the sound waves astronomers previously identified were extracted and made audible for the first time. The sound waves were extracted outward from the center. (source)