Totally sentimental view on my part, but I consider the JPL ephemeris files one of the crowning achievements of humankind. On par with other things like a moder

Totally sentimental view on my part, but I consider the JPL ephemeris files one of the crowning achievements of humankind. On par with other things like a modern microprocessor, the pyramids, or the electric grid. You of course know this, saying it for others: The files themselves are relatively unassuming, moderate sized (~3.1 GB the largest of them) binary files which contain the distilled best knowledge of where the planets and their moons will be based on humanity's best observations (visual, radar, trajectory data from probes, etc). They each have a validity window within which you can query the relative transforms between the objects the database contains. For example de441.bsp was published in 2020 and you can use it to predict the relative positions of any of the planets/moons it contains between the years −13200 to 17191. Or if you don't need to look that far in time you can use one of the smaller models like de440s.bsp (32 MB) which is good between 1849 to 2150.