[fppcmwbw] Pointing the way to Jupiter

I'm surprised that it takes less energy to get to Jupiter than to get to the Sun, even without gravity assists (slingshot maneuvers) from other planets.

Create a moving "arrow" sculpture which always points in the direction one would launch an unpowered projectile for it to hit Jupiter.  It's a complicated gravity calculation.  We probably want the vector that minimizes launch velocity, also depicted somehow.

Launching into the Sun is rather more boring: against the direction of earth's orbital motion, corrected for the rotation of the earth.  Some part of each day it's not possible, needing to launch into the ground.

Inspired by the Arrow of Apollo. Might make a nice addition to the Boston Museum of Science's solar system model; Jupiter is at South Station.