# Interplanetary Distances Calculator

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Did a search over the forums, and the internets, and thus far have come up with nothing whatsoever. I'm working with a friend to create an original SF setting in the year 2176, and we thought it was pretty important to have actual interplanetary distances on the start date of the setting (1/1/2176). At first I was just going to copy directly from the Transhuman Space book that lists distances as of 2100, but I really would like to avoid just stealing their work.

So, my question is this: does anyone know of an online program that calculates the distances of all the planets and (hopefully) all of the major asteroids from each other as of a given date? And if there's not a program available, how would one go about figuring that out?

Thanks guys, I know that if anyone could help me out with this, they're in this forum.

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Re: Interplanetary Distances Calculator

One of the problems is even if you had locations of all the planets you'd need to plot flightpaths from getting from one to the other. And getting those requires knowing what kind of ship/drive/tech is making the trip. And math, lots of it.

I used to have a astronomy program that would tell you what the stars in the sky looked like (with planets) that you could adjust the date to see what it looked like at different times. Name of the program was Starry Night. I might be misremembering though, it was a while ago.

Another thought would be to find some astrology sites. While I try to avoid the stuff, The Wife has a mild interest in it. They like to pay attention to where the planets are for portents, etc. Might be worth a search. Won't help with travel times, might might get locations.

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Re: Interplanetary Distances Calculator

There are several "desktop planetarium" codes you can snag free trial copies of, but after a few months they go belly-up. The real versions are pricey; Voyager 4.5 is \$180 (for physical media; \$100 for a download), looks like.

MICA is from USNO and costs \$30; the order location is here. It is less sexy but has, it sounds, what you want. It also runs on old platforms, which is important to some of us who still keep a Win98 box at home.

I'll keep looking around and if I find something long-lasting and free I'll edit this post.

EDIT: You can get software patches with asteroid ephemerides for a number of "desktop planetarium" codes from the Minor Planet Center (link). I am not familiar with any of the codes named on that page, though it looks like they are old ones.

EDIT^2: If you have the stomach for it ... and it is in High Techspeak ... you can get "low-precision formulas" for planetary positions from the technical literature from this paper. Unfortunately, that has only the planets; no asteroids. And those are strictly Earth-centered formulas, so you'll have a bit more work to get something like (x,y,z) coordinates .... All told, this approach is probably not worth it for you unless you really want to delve into the stuff....

EDIT^3: A starting point for looking for data like this in JPL's website is here ... it'll be a while before I can delve through that and look for on-point tidbits.

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