Update project
More precise approximation of velocity (not measured, just waving my hands)
Add Mars data
Add a quick set of functions for rendering some coloured axes for the planets.

From this we can see that the axes from the ephemeris calculations look good; the only problem is the earth-moon system has Y as being the orbit normal instead of Z.
Fix camera and earth-moon system so that Z is up throughout.
Give Earth a label and update labels in Entity update
Add a helper function for spawning bodies
Add Mercury, Venus and Mars
Add rest of 'classic' solar system (includes Pluto).

Next I'll want good data on: Earth-moon, Eris, Ceres, asteroids, satellites, moons of Jupiter and Saturn...