Not sure how to make a title for this idea, perhaps someone can suggest a better title, but basically would be nice to have a place for ideas on things that can be added to Space Engine that will help us picture and visualise and comprehend the things we are trying to picture and visualise and comprehend when we use this to-scale photo-realistic universe simulator.
I'll add my own of course too, starting with this:
-How about a setting that turns on this: When we are travelling at various speeds, certain familiar objects, each appropriate to the current velocity, repeatedly pass us (or rather we pass it). So if we are travelling anywhere from 100,000km/s to 100c, we pass the earth over and over and over, to help us imagine how fast we are going.
The thing about picturing the vast velocities of the universe is we have no frame of reference as space is so astonishingly empty, and even if it weren't, there aren't many things we can relate to, at ultra high velocities. We can at least work our way up a bit, and this idea is also useful just for "relative" understanding of velocities, in the same way a non-pitch-perfect musician can learn to work out which key is being played from hearing another known key in the last few seconds.