I wasn't quite able to figure it out, but feels like I was on the right track? Getting the distance of the planets was fine, and to get the speed I timed how long it took between each time the planet passed the window. I'm guessing I missed a step when entering them into the model though - do you need to calculate the actual orbital speed of the planet using distance and time and then sequence them accordingly? Genuinely intruiged as to how this works.
This works so, so well as a tone piece, from the cryptic story to the sight of the End of Everything slowly approaching with it's backwards orbit as you're watching the planets
The music here is absolutely superb, it feels deeply ominous but also somehow awe-inspiring, in a manner totally befitting the Scale of the End of Everything.